• Russia angered by Nato summit

• Obama hopeful, but sceptical, about Ukraine ceasefire

• Ceasefire deal signed, came into effect at 4.00pm BST

• New Russia sanctions target oil, may be lifted with ceasefire

• Heavy artillery fire earlier outside Mariupol

• Cameron: Russia is ripping up the rulebook in Ukraine

• UK commits 3,500 troops to Nato response force in Poland

Latest

20.00 We're going to leave it there for the night. Please check our Ukraine page for the latest.

19.05 President Obama has made an unscheduled stop on the way out of Wales: Stonenhenge.

"How cool is this?" he said to reporters. "Knocked it off my bucket list."

-

18.55 All seems quiet in Ukraine since the 4pm ceasefire - for now.

18.46 This analysis of prospects of peace in Ukraine, from Quartz, is worth a read.

The ceasefire signed today by Ukraine’s combatant forces seems to lack any resolution on the pivotal issue underlying the war—whether Ukraine will have the right to follow the political and economic path it chooses. Unless there’s another announcement forthcoming, that’s why the truce is unlikely to hold.

18.27 And in the US, a plane heading towards Florida is described by US authorities as "unresponsive".

It's now heading towards Cuba.

We'll keep you updated.

18.04 Russia's foreign ministry has reacted angrily to Nato's declaration.

The essence and tone of [Nato] statements on the Ukraine situation, and the plans announced to hold joint Nato exercises with Kiev on the territory of that country before the end of 2014, will inevitably lead to heightened tension.

They risk wrecking the progress made in the peace process in Ukraine, and encourage a deepening of the split in Ukrainian society.

17.56 Russia has just published its version of events surrounding the detention of an Estonian man.

Here it is in full, via the Russian official news agency:

MOSCOW, September 05. /ITAR-TASS/. An officer of the Estonian security police was detained on Friday on the territory of Russia’s north-western Pskov region while he was conducting an undercover operation, the public relations center of the Federal Security Service told ITAR-TASS.

“A citizen of Estonia, Eston Kohver, who is an officer of the Estonian security police bureau, was detained on the territory of the Russian Federation,” the press center said. “He had a Taurus handgun, an amount of €5,000 in cash, equipment for covert audio recording, and materials indicative of an intelligence mission."

17.42 But on the ground in eastern Ukraine, things are perhaps not so rosy.

The BBC's Richard Galpin tweets:

<noframe>Twitter: Richard Galpin - 1 of pro <a href="https://twitter.com/search?src=hash&q=%23Russia" target="_blank">#Russia</a> rebel leaders in <a href="https://twitter.com/search?src=hash&q=%23Donetsk" target="_blank">#Donetsk</a> tells me their plan is still 2 create independent state inc all east <a href="https://twitter.com/search?src=hash&q=%23Ukraine" target="_blank">#Ukraine</a> +across to <a href="https://twitter.com/search?src=hash&q=%23Odessa" target="_blank">#Odessa</a></noframe>

17.32 More from Ban Ki-moon.

The UN Secretary General welcomed a ceasefire in eastern Ukraine and stressed that "credible and comprehensive monitoring and verification are essential elements for successful implementation."

A UN spokesman added:

He also welcomes the recent discussions between the presidents of Ukraine and Russia that have played a part in today's breakthrough and strongly encourages those contacts to continue.

17.29 Unsurprisingly, Ukraine's pro-Kiev PR unit is quick to respond to today's events.

<noframe>Twitter: Euromaidan PR - <a href="https://twitter.com/search?src=hash&q=%23Putin" target="_blank">#Putin</a> has good day:1)'wins' in <a href="https://twitter.com/search?src=hash&q=%23Ukraine" target="_blank">#Ukraine</a>; 2)kidnaps <a href="https://twitter.com/search?src=hash&q=%23Estonian" target="_blank">#Estonian</a> agent,thumbs nose at <a href="https://twitter.com/search?src=hash&q=%23Obama" target="_blank">#Obama</a>; 3) <a href="https://twitter.com/search?src=hash&q=%23Merkel" target="_blank">#Merkel</a> suggest softening sanctions <a href="http://www.twitter.com/mel_huang" target="_blank">@mel_huang</a></noframe>

17.21 U.N. CHIEF BAN KI-MOON WELCOMES UKRAINE CEASEFIRE, SAYS 'CREDIBLE, COMPREHENSIVE MONITORING AND VERIFICATION' ESSENTIAL FOR SUCCESSFUL TRUCE

17.20 So here is a brief summary of the key points from Obama's speech, at the close of the Nato summit:

- Obama "confident" that an international coalition against Isil can be reached

- President hopeful, but sceptical, about Ukraine ceasefire

- United States and Europe are finalising measures to deepen and broaden sanctions across Russia's financial, energy and defence sectors

With respect to the ceasefire agreement, obviously we are hopeful but based on past experience also sceptical that in fact the separatists will follow through and the Russians will stop violating Ukraine's sovereignty and territorial integrity. So it has to be tested.

17.16 Obama is wrapping up his speech - with a final question about American immigration reform...

17.10 People are already beginning to say that Obama appears far more decisive and resolute today than he did on Wednesday, when he last spoke, from Estonia.

Zeke Miller, political reporter with Time magazine, tweets:

<noframe>Twitter: Zeke Miller - Obama Friday vs. Obama Wednesday are like two different people</noframe>

17.09 The US president says that they will take on Isil in the same way they have countered al-Qaeda and al-Shabaab.

He references the death of Godane (see 16.51).

For more on why the killing of al-Shabaab's leader is so significant, read Colin Freeman's profile of him.

Ahmed Abdi Godane: the al-Shabaab leader targeted by air strikes

17.03 Obama continues talking about Isil.

What we have learned in Iraq is yes Isil has terrorist capabilities.

But part of the problem is that we haven't seen as effective a fighting force as we need.

We have to bolster them, bolster the work the Peshmerga has done... We also need the Sunni tribes in various areas to realise that their future lies not with the kind of future that Isil presents.

We are working deliberately.

We've taken this in stages.

He says that the third stage will be "to take the fight to Isil" - and make sure that "we are doing it right" with a strong strategic communications effort, and tackling the right targets.

17.02 Obama has now moved on to talk about Isil.

Our hope is that the Iraqi government is formed in the next week.

He says that the US has been assisting Iraq with humanitarian supplies, surveillance equipment and advice.

17.01 Obama: "We mean what we say when we talk about our Article 5 commitments."

There's a lot of talk about Article 5 - here's an explanation of what it is.

In summary:

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all

17.00 Obama is asked about Russia.

He says:

The path for Russia to rejoin the community of nations that respects international law is still there - and we urge President Putin to take it.

Big countries can't just stomp on little ones, or force them to change their policies and give up their sovereignty.

16.57 He says that new members can join Nato.

We reaffirm that the door to Nato membership remains open to those who can meet our high standards.

He mentions Georgia, Moldova, Jordan and Libya.

16.55 All 28 Nato nations have pledged to increase their contributions to defence spending, up to 2pc of GDP, Obama says.

This commitment makes clear that Nato will not be complacent.

16.52 Obama has begun speaking. He begins by stating how "Russia's aggression over Ukraine" is a threat.

But he emphasises that Nato has reaffirmed that it has "the will, the resources and the capability" to counter it.

16.51 The Pentagon has just confirmed the death of Ahmed Abdi Godane, leader of al-Shabaab in Somalia.

Which is a great way for Obama to begin his speech...

16.48 We're expecting to hear from Barack Obama any time now, at the end of the two-day Nato summit in Wales.

16.30 The Nato summit, held at Celtic Manor in Newport, is drawing to a close soon.

Photos are coming in of the Red Arrows flypast earlier today.

16.04 Reuters: Minutes after the ceasefire was due to come into force, three explosions were heard north of the city of Donetsk. It was not immediately clear how serious the blasts were.

16.02 The ceasefire officially began two minutes ago:

<noframe>Twitter: Roland Oliphant - The guns are silent.</noframe>

16.00 David Cameron insists the West has been tough on Putin over the Ukraine crisis:

I would challenge the view that the EU, the West and America have somehow been weak in response to what has happened.

It's important to focus on the pressure we can realistically bring to bear, and that is economic.

Russia needs the West more than the West needs Russia.

15.58 Cameron denies backing down to Russia over Ukraine

We are not accepting a partition of the Ukraine.

That is why we have taken the sanctions, that is why we have piled on the pressure.

The announcement of the ceasefire is good news.

We need to look at the detail of that to make sure it happens.

The sanctions will go ahead... if a ceasefire and a proper peace plan go ahead, then it would be right to see [if sanctions can be lifted]

15.50 David Cameron is now speaking about the ceasefire at the Nato summit:

There has been a clear message sent from this conference that what Putin has been doing is wrong.

We stand firmly behind Ukraine's right to make its own decisions, not to have them taken by Russian tanks rolling across the border.

Any member not hitting the Nato target of 2 per cent of GDP spent on defence has agreed to freeze defence cuts. Of course, that does not commit any members to meeting the 2 per cent in the future...

15.48 President Vladimir Putin's spokesman, Dmitry Peskov, has issued a statement approving the ceasefire deal:

The Russian presidential office welcomes the signing of the protocol in Minsk," Interfax news agency quoted

Moscow hopes all the provisions of the document and the agreements reached will be thoroughly observed by the parties and that the negotiating process will continue until the crisis in Ukraine is fully resolved."

15.42 Anders Fogh Rasmussen remains sceptical about the Ukraine ceasefire:

One thing is to declare a ceasefire... the next and crucial step is to implement it in good faith.

But so far so good. I hope that this step could be the start of a constructive political process.

15.40 Meanwhile inside the hall Anders Fogh Rasmussen, the Nato secretary-general - presumably not delighted that Poroshenko coincided his statement with the press conference - tells the hall it is not acceptable that while Russia has increased its defence spending by 50 per cent, Europe has reduced its own by 20 per cent.

David Cameron and Barack Obama watch a flypast on the second day of the Nato Summit in South Wales (LEON NEAL/AFP/GETTY)

15.38 Poroshenko, the Ukrainian president, emphasised that the deal emerged from talks with Russia - despite Moscow's claims it was not a party in talks

15.33 Petro Poroshenko is now giving a statement from outside the Nato summit in Wales

There are 12 practical steps to establish peace and stability in part of the Luhansk and Donetsk regions of Ukraine

Based on this agreement I give an order to the chief of my military to declare a ceasefire in half an hour, at 6.00pm Ukrainian time

It is very important the ceasefire lasts a long time... and we continue a political dialogue

There is also a roadmap with a practical date when every single point from the 12 should be undertaken

We expect in the very near future to release the hostages, probably tomorrow

Significant steps [have been taken] including decentralisation of power... which guarantee economic freedoms and the rights to use any languages on this territory

I am very satisfied with the results of the [Nato] summit and I think it is very symbolic that the ceasefire was agreed during this summit

This peace process is based on my peace plan... and on the territorial integrity and sovereignty of my country

15.25 News of the ceasefire deal has been greeted with heavy scepticism by Nato officials in Wales. Ben Farmer reports from Newport:

The British General who is Nato's deputy commander in Europe reacted cautiously to reports of a ceasefire and said he would pay attention to the Kremlin's actions, rather than words.

Gen Sir Adrian Bradshaw, Deputy Supreme Allied Commander Europe, said: "We look at actions fairly carefully. We have heard quite a lot of words; some of those words have proven to be not worth terribly much. There's been some deception and deceit. Right now I can't tell you there has been any substantial change to the reality on the ground.

He said "Russian regular armed forces" were still deployed in support of the separatists.

15.20 Separatist leaders have warned that the ceasefire will only last as long as there is no shooting from the Ukrainian side. "If even one provocative shot is fired by the Ukrainian army then the ceasefire will be annulled straightaway," a separatist spokesman told Russian news agencies.

15.05 Both sides now appear to have agreed the ceasefire will begin from 6.00pm local time, which is 4.00pm BST. Howard Amos, in Moscow, explains what we do and don't know about the ceasefire deal so far:

Both Kiev and separatist leaders have now confirmed they have signed a ceasefire that will come into effect at 6pm local time.

"I order the Chief of the General Staff of the Armed Forces of Ukraine to cease fire starting from 18:00, September 5... I also instruct the Minister of Foreign Affairs of Ukraine to ensure jointly with the OSCE an efficient international control over the compliance with the ceasefire regime which must be exclusively bilateral."

In turn, the separatist leaders also said they were giving an order to lay down arms.

“We confirm our readiness to fuflfill the signed protocol and cease fire at 18:00 Kiev time,” said Igor Plotnitsky, the head of the self-proclaimed Lugansk People's Republic said in Minsk, Russian news agency RIA Novosti reported.

While the details of an wider peace agreement have yet to emerge, the separatist leaders made it clear that they are still looking to carve out an autonomous state in east Ukraine.

“We intend to continue our policy of detachment [from Ukraine]. The ceasefire is an enforced measure. There is a lot of work ahead,” said Plotnitsky, according to RIA Novosti.

Participants at the Minsk talks, which also include representatives from the OSCE and Russia, have reportedly returned to the negotiating table after making the public announcement of a ceasefire between the Ukrainian army and rebel forces.

Talks in Minsk (AFP)

14.50 Could the threat of EU sanctions on Russia - which may yet be lifted under a ceasefire deal - have prompted action? Here are the draft EU sanction proposals currently being discussed in Brussels by EU ambassadors:

Additional restrictions on access to the capital market should be imposed in relation to state-owned Russian financial institutions, Russian entities in the defence sector, and Russian entities whose main business is the sale or transportation of oil.

Furthermore, the sale, supply or transfer of certain dual-use items to Russia or for end-use in Russia should be prohibited.

In addition, the provision of services for deep water oil exploration and production, arctic oil exploration and production or shale oil projects should be prohibited.

Furthermore, the sale, supply, transfer or export of hydrocracking and desulphurisation technologies or equipment should be prohibited.

Further action by the Union is needed in order to implement certain measures.

14.45 Forty-five minutes into the ceasefire, and Kiev has given its troops the order to halt their fire - but not until 4.00pm BST (6.00pm local time).

Roland Oliphant reports from the frontline at Mariupol:

Very heavy fire edging closer to the main Ukrainian eastern checkpoint in Mariupol. But no panic in the city. Wedding motorcade of stretched limos just passed me honking happily, oblivious to the crump of shelling

14.30 Petro Poroshenko, Ukraine's president, has described the deal as a "preliminary truce" on his Twitter account, suggesting there is a lot more negotiaiton to be done before this can be seen as a decisive peace deal.

There are also reports that the so-called Luhansk People's Republic intends to continue pushing for a split from Ukraine, despite agreeing to today's deal.

14.23 The ceasefire deal was announced by members of a trilateral group containing Ukraine, Russian and OSCE representatives, who have now returned to the Minsk meeting room, AP reports:

"Immediate ceasefire from 6pm Minsk time" pic.twitter.com/Kemx2Z4FoW — Alexander Roslyakov (@RoslyakovAP) September 5, 2014

14.15 Pro-Russia rebels have now said on Twitter they have signed cease-fire deal with Ukraine.

Meanwhile, Ukraine's prime minister Arseniy Yatsenyuk has called for the United States and Europe to act as guarantors to the ceasefire:

It must be supported by the United States and the EU. We will not manage with Russia on our own... we need guarantees

14.09 Our Moscow correspondent, Roland Oliphant, says that there is some confusion over the timings of the ceasefire, however...

<noframe>Twitter: Roland Oliphant - In Wales, <a href="http://www.twitter.com/poroshenko" target="_blank">@poroshenko</a> says 17:00. On Twitter, <a href="http://www.twitter.com/press_dnr" target="_blank">@press_dnr</a> says 18:00. In Minsk, <a href="http://www.twitter.com/NatVasilyevaAP" target="_blank">@NatVasilyevaAP</a> says talks on going. <a href="https://twitter.com/search?src=hash&q=%23ceasefire" target="_blank">#ceasefire</a></noframe>

14.04 Petro Poroshenko, the Ukrainian president, has announced that there will be a ceasefire from 4pm - ie: in an hour's time.

13.59 Philip Breedlove, Nato's supreme allied commander for Europe, has just tweeted his support of Nato's announcement.

<noframe>Twitter: Phil Breedlove - Readiness action plan ensures that thousands of our troops will be prepared to deploy in just a few days if needed. <a href="http://t.co/NkqtEd9P8q" target="_blank">http://t.co/NkqtEd9P8q</a></noframe>

13.45 Breaking news - MERKEL SAYS NEW EU SANCTIONS AGAINST RUSSIA CAN BE SUSPENDED IF DE-ESCALATION OCCURS IN UKRAINE

13.41 Meanwhile in Moscow, the new US Ambassador to Russia has just arrived.

John Tefft, who was sworn in by John Kerry earlier this week, tweeted in Russian: "I am very happy to be back in Russia. I am looking forward to interacting and working with Russians representing all strata of society."

He was deputy chief of mission at the US embassy in Moscow from 1996 to 1999.

13.15 Roland Oliphant, the Telegraph's correspondent on the ground in Ukraine near Mariupol, addresses those claims earlier on that rebels had seized the key port city:

<noframe>Twitter: Roland Oliphant - Panicked calls asking if rebel claims of entering mariupol are true. They are not, as far as I can tell.</noframe>

Meanwhile, ceasefire prospects are not looking any brighter:

<noframe>Twitter: Shaun Walker - Poroshenko apparently tells <a href="http://www.twitter.com/BBCHARDtalk" target="_blank">@BBCHARDtalk</a> he's "absolutely not confident" over lasting ceasefire. We're all clear on that then.</noframe>

12.49 A few announcements there that will not be warmly received in Russia:

• The next Nato summit will take place in Poland

• A new rapid response force will be set up in eastern Europe

• Any aggression against its member in eastern Europe will be seen as an attack on all

• The door is open to new members in eastern Europe including Georgia

12.43 Nato Secretary-General Anders Fogh Rasmussen is now announcing Nato's agreements in Wales today to strengthen Nato's forces, including the creation of a rapid response force and placing cyber-defence at the core of its strategy.

Ties with non-Nato partner nations will also be strengthened, including more opportunities to train alongside Nato forces, he announces.

Jordan, Moldova and Georgia become partners, he says, while Libya and Iraq will be offered extra assistance.

Aspiring members will be offered support in their joining process. A "substantive package" to help Georgia advance in its preparations towards membership of Nato has been agreed.

Talks will be opened and intensified with Montenegro, with a decision by 2017 on whether an invitation will be extended.

Prime Minister David Cameron speaks during the Nato Summit in Newport

12.40 As the 2.00pm 'ceasefire' proposed by Petro Poroshenko, Ukraine's president, comes and goes without trace, Howard Amos, in Moscow, explains the confusion currently surrounding peace talks in Minsk:

As the Minsk talks aimed at brokering a peace deal in eastern Ukraine get underway, there is confusion over the timing of any ceasefire.

Ukrainian President Petro Poroshenko appeared to say on Thursday that the beginning of the Minsk talks were his only precondition for the ceasefire.

"At 2pm local time on Friday, provided the meeting takes place, I will call on the general staff to set up a bilateral ceasefire,” Poroshenko said.

In contrast, separatist leaders said on Thursday that they would only order a ceasefire – also at 2pm local time – if Kiev signed up to a peace plan in Minsk.

“On 5th September at 15:00 Moscow time we are prepared to give the order for a ceasefire if we succeed in reaching an agreement and Ukrainian representatives sign a plan to for the political settlement of the conflict,” the self-proclaimed Donetsk People's Republic and Lugansk People's Republic said in a statement, Russian media reported.

The talk in Minsk have now begun – at 2pm local time – but there is no word yet from either Poroshenko or the separatist leaders on a ceasefire.

12.23 All parties at the Minsk talks have apparently arrived, and talks are underway. AFP reports:

"We have come here for peace," Ukraine's representative, former president Leonid Kuchma.

"We will talk about a ceasefire and what needs to be done for it," he told reporters ahead of the talks between what's known as the Contact Group.

"I hope they will agree on something," Russia's ambassador to Minsk Alexander Surikov said for his part.

Russia's representative in the Contact Group, Moscow's ambassador to Ukraine Mikhail Zurabov, said he expected documents to be signed, but he wouldn't elaborate.

The separatists are represented by leaders from the self-proclaimed Donetsk People's Republic and Lugansk People's Republic, including rebel prime minister Alexander Zakharchenko.

12.00 Conflicting reports emerging from Mariupol.

Russia's Interfax agency has just reported that pro-Russian rebels claim to have 'entered' the city - only for a Ukrainian military spokesman to immediately brief that Mariupol is still in government hands.

"The first (rebel) groups ... are already in Mariupol," Interfax quoted a rebel source as saying.

Andriy Lysenko, spokesman for Ukraine's National Security and Defence Council, said in Kiev: "It is not true. We have even driven them back from the positions they held before."

More details as we get them.

11.51 The Minsk talks aimed at negotiating a peace plan between Kiev and the separatists have now begun, officials say, less than 10 minutes before the 2.00pm local time deadline at which Petro Poroshenko said yesterday he would declare a ceasefire.

It is not clear on whether that declaration will still happen, as it was seen as likely to be contingent on an agreement in Minsk. There is the additional problem of ongoing heavy artillery fighting near Mariupol.

11.40 Ukrainian television is reporting that the efforts to repel separatists outside Mariupol may not be limited to Kiev government troops:

<noframe>Twitter: Oliver Carroll - Far-right football fans brought in to defend Mariupol, trained by controversial Azov battalion, reports <a href="http://www.twitter.com/HromadskeTV" target="_blank">@HromadskeTV</a> <a href="http://t.co/H4vZgHJloV" target="_blank">http://t.co/H4vZgHJloV</a></noframe>

Volunteer soldiers from new battalion Mariupol take the oath of allegiance to Ukraine during a rally in the south eastern Ukrainian city of Mariupol (EPA/ANATOLY MALTSEV)

11.25 With just 35 minutes to go until the ceasefire discussed yesterday is supposed to begin, heavy artillery bombardments continue outside Mariupol. The Telegraph's Roland Oliphant reports from the scene:

Just a few miles east of Mariupol, intense artillery barrages could be heard and smoke could be seen rising from artillery strikes around the village of Shirokino.

The shelling this morning was much further east than last night's, when it took place within a mile of Mariupol's eastern checkpoints.

It is now five to 10 miles down the road in the no-man's land between Mariupol and Novoazovsk

11.10 Bruno Waterfield, our Brussels correspondent, has the latest on the new EU sanctions against Russia to be discussed at the Nato summit this afternoon:

EU sanctions, in concert with the US, will strike at the mainstay of Russia's economy by cutting oil companies off from Western investors along with the country's state-owned banks which cut off from European capital markets in August.

Russia's defence industry is also targeted amid a tightening up of ban on the export of Western technology and oil exploration services.

A list of Russian oligarchs targeted as Vladimir Putin's cronies for asset freezes and travel bans will also be published next week.

The sanctions are a warning to the Russian president that unless he pulls out troops the EU will continue to tighten the stranglehold on Russia's economy.

"In view of the gravity of the situation the Council considers it appropriate to take further restrictive measures in response to Russia's actions destabilising the situation in Ukraine," said a draft EU legal text to be agreed by ambassadors on Friday afternoon.

More names and companies are to be added to a blacklist next week whic has been expanded to "natural or legal persons, entities or bodies conducting transactions with the separatist groups in the Donbass region of Ukraine."

10.58 So, what is the peace plan set to be discussed in Minsk? Roland Oliphant explains:

A peace plan, published by the Kremlin, requires both sides to cease offensive operations. Ukrainian troops would also have to “withdraw to a distance that rules out the possibility of populated areas being fired upon by all forms of artillery and multiple rocket launchers”.

International monitors would then arrive and “corridors” for aid and reconstruction would be opened.

But the clause requiring Ukrainian forces to withdraw would leave large areas of Donetsk and Luhansk regions, including their two capitals, under the control of the armed separatists.

Western diplomats believe that Mr Putin’s “endgame” is to “freeze” the conflict by creating an autonomous region in eastern Ukraine that would depend on Russian patronage, following the example of the territories of South Ossetia and Abkhazia in Georgia, and Transdnistria in Moldova.

A wounded Ukrainian army soldier is evacuated by a medical team as pro-Russian separatists fire heavy artillery, on the outskirts of the key southeastern port city of Mariupol (PHILIPPE DESMAZES/AFP/GETTY)

10.50 It's looking like the start of talks in Minsk has been delayed, reports Howard Amos from Moscow:

They are now due to kick off at midday London time. Which means ceasefire very unlikely to be announced at the expected time (midday in London, 14:00 local time).

10.31 Kiev's fightback against separatist rebels outside Mariupol appears to be making some progress:

<noframe>Twitter: Shaun Walker - Lots of heavy armour at position E of Mariupol now, arrived overnight. Rebels pushed from 5km away to 20km, they say. <a href="http://t.co/sgRTsJ78UK" target="_blank">http://t.co/sgRTsJ78UK</a></noframe>

10.25 No word yet from Minsk, where peace talks involving Kiev and rebel leaders were due this morning ahead of the proposed ceasefires. Itar Tass, a Russian news agency, is reporting that the prime ministers of the Donetsk and Luhansk self-proclaimed republics, Alexander Zakharchenko and Igor Plotnitsky, will attend on behalf of their regions.

Citing Donetsk deputy prime minister Andrei Purgin, the agency reports that the Russian ambassador in Ukraine, Mikhail Zurabov, as well as former Ukrainian president Leonid Kuchma and OSCE special envoy for Ukraine Heidi Tagliavini will also take part in the third meeting of the contact group.

The first two meetings took place on July 31 and September 1.

10.00 Roland Oliphant, our Moscow correspondent currently in Mariupol in Ukraine, is not finding today's peace talks especially peaceful:

<noframe>Twitter: Roland Oliphant - Good morning from (boom) Mariupol. It's peace talks (bang) and cease (boom) fire day. By 14:00 apparently.</noframe>

09.40 Nato secretary-general Anders Fogh Rasmussen has opened today's Nato summit press conference, saying Nato must show it is willing and able to defend its members and boost defence spending.

David Cameron speaks:

The vision of a Europe whole free and peace seemed within our grasp. Yet the protection Nato provides is as vital now as in the past...

In the east, Russia is ripping up the rulebook [in Ukraine]... as Russia tramples illegally over Ukraine we must reassure our eastern European memebers we will always uphold our Article 5 commitments to collective self-defence

He speaks about a new rapid response force headquartered in Poland, to which he says the UK would commit 3,500 personnel. He also says he hopes to reaffirm the UK's commitment of spending 2 per cent of GDP on armed forces.

Red Arrows airplane display team perform a flypast over the Nato 2014 Summit at the Celtic Manor Hotel in Newport (CARL COURT/AFP/Getty Images)

09.35 Yuri Khotlubey, the mayor of Mariupol - which is the reported target of a separatist assault - has spoken to Ukrainian TV about Kiev forces' attempt to repel any offensive:

Our artillery has come and is being deployed against the [pro-Russian] rebels

As he spoke, Reuters witnesses in Mariupol heard artillery shelling a few miles to the east of the centre.

A commander of a Ukrainian volunteer militia based in Mariupol told Reuters by telephone that his battalion had been under sustained rebel fire all night into Friday.

We are still keeping the rebels at bay. They are confronting us with tanks and artillery

Mariupol is a port city of around 500,000 on the Sea of Azov crucial for its steel exports. It stands about halfway between Russia and the Russian-annexed Crimea region.

Soldiers of Ukrainian self-defence battalion "Azov" guard their position at a checkpoint in the southern coastal town of Mariupol (REUTERS/Vasily Fedosenko)

09.27 New sanctions against Russia expected to be announced on Friday in response to the Ukraine crisis could be lifted if a ceasefire is implemented, Britain's Foreign Secretary Philip Hammond has said:

What would be sensible is to go ahead with our plan for increased sanctions.

If there is a ceasefire, if it is signed and if it is then implemented, we can then look at lifting sanctions off

But... there is a great deal of scepticism... if this deal will materialise

09.16 Swedes and Poles are the Europeans most willing to risk conflict with Russia to support Ukraine, Sweden's ambassador has tweeted.

The claim is based on a poll carried out by Transatlantic Trends, which is run by the German Marshall Fund of the United States and Italy-based Compagnia di San Paolo

The UK ranks as more willing than most of our EU allies, with 59 per cent of those polled agreeing.

<noframe>Twitter: A von Beckerath - Swedes (73%) most willing to help Ukraine even if it worsens conflict with Russia. Via <a href="http://www.twitter.com/VandaCzifra" target="_blank">@VandaCzifra</a> <a href="http://www.twitter.com/andersostlund" target="_blank">@andersostlund</a> <a href="http://t.co/UIaQVD36kN" target="_blank">http://t.co/UIaQVD36kN</a></noframe>

09.10 We expect today at the Nato summit to hear confirmation of the alliance's proposed 10,000-strong rapid deployment force in eastern Europe.

09.00 Philip Hammond, the Foreign Secretary, is speaking on BBC News from Wales at the Nato summit. He is asked why Britain does not simply provide Kiev with weapons to fight the Russia-backed separatists:

Because there can't be a military solution to this conflict, there has to be a political solution.

Russia has to live with the fact that Ukraine has made a choice that it wants to be part of the European family, but in no way antagonistic [toward Russia]... that Ukraine wants to and has to live with Russia as a big and powerful neighbour for the future.

08.30 AP has more on the reported assault on Mariupol this morning:

Shelling resounded on the outskirts of a Ukrainian port city Friday as Russian-backed rebels pressed their offensive in the strategically key southeast just hours ahead of talks that are widely hoped to bring a cease-fire.

Associated Press reporters heard heavy shelling on Friday morning north and east of Mariupol. The strategic city of about 500,000 lies along the Sea of Azov, between Russia to the east and the Russia-annexed Crimean Peninsula to the west.

The sound of incoming and outgoing shelling from different directions appeared to indicate that rebels have partially surrounded the area and are probing its defenses. The onslaught could be intended to raise the pressure on the Ukrainian government ahead of peace talks in Minsk, Belarus, which are expected to lead to a cease-fire.

Seizure of Mariupol would give the rebels a strong foothold and raise the threat of the rebels carving a land corridor between Russia and Crimea, the Black Sea peninsula that Russia annexed in March. If that happens, Ukraine would lose another chunk of sea coast and access to rich hydrocarbon resources the Sea of Azov is believed to hold.

08.00 Roland Oliphant reports from Mariupol, in eastern Ukraine, on the obstacles to a ceasefire today:

If all goes well, Petro Poroshenko will order Ukrainian forces to ceasefire at 14:00. The separatists have said they will follow suit an hour later if the Ukrainians keep their word.

This is the closest we have been to an end to this conflict in the past five months, but there are several stumbling blocks that may yet torpedo hopes of finding a settlement.

First of all, all sides - Ukraine, the Separatists, and Russia, have different ideas of what peace should look like.

Russia’s plan, for example, which was unveiled by Vladimir Putin on Wednesday, calls on both sides to cease offensive operations, but only on the Ukrainians to withdraw - effectively handing the separatists full control of the Donbass.

That will likely be unacceptable to the Ukrainians, who will be conceding a great deal in agreeing to a ceasefire even without a withdrawal.

As in many insurgencies, all the rebels have to do was avoid defeat. A ceasefire is tacit recognition that Kiev cannot end this crisis by military means - and effectively secures the rebel’s control of the ground they have captured. In effect, it means a rebel - and Russian - victory.

On the ground, however, such a ceasefire still seems a remote possibility.

Separatist artillery renewed its bombardment on the outskirts of Mariupol at first light on Friday, while shelling could also be heard around the rebel stronghold of Donetsk.

Full report:

Kiev and separatists met in Minsk for Ukraine peace talks

07.30 Good morning and welcome to our live coverage of a crucial day for the Ukraine crisis.

Both Ukrainian president Petro Poroshenko and separatist rebel leaders have pledged to declare a ceasefire at around noon BST today, if a peace plan is agreed upon this morning in talks in Minsk, the Belarussian capital.

But with reports of fighting overnight and this morning in the southern Ukrainian port town of Mariupol – still in Kiev hands – and the rebel stronghold of Donetsk, nothing can be taken for granted.