Prime Minister John Key speaks to media after chairing the United Nations Security Council meeting on Syria.

An impassioned debate on Syria at the Security Council has given the main players a chance to "hit the reset button", Prime Minister John Key says.

Key lashed the international community for "failing" Syria, while chairing a United Nations Security Council debate at the UN headquarters in New York.

New Zealand, which is a temporary member of the Security Council, had put Syria on the agenda - and Key said we did the right thing.

UN WEB TV Prime Minister John Key has the attention of 193 member nations as he addresses the UN General Assembly.

The prime minister chaired the meeting at which US Secretary of State John Kerry delivered a scorching condemnation of Russia over its backing of Ashar al-Assad's Syrian regime.

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"We used our time in the presidency to address the single biggest issue we are all facing now," Key said."

UNITED NATIONS Prime Minister John Key, flanked by Foreign Affairs Minister Murray McCully, speaks to media after his speech at the UN Security Council.

"There was a bit of venting, a bit of frustration...but what other place can they continue to have those discussions?

"We have to accept that every step along the way here there's a need to hit the reset button. Today was a chance to hit the reset button.

Earlier, Key told international media there had been a lot of emotion in the room during the debate, but everyone was agreed that the only way forward for the people of Syria was for the ceasefire to hold.

"And while the process was always going to be challenging, a little bit messy; sometimes two steps forward and one step back - in the end if we fail to find a way forward for the people of Syria, more innocent people will lose their lives and the responsibility of that ultimately has to rest on the people at that table and those who have the strongest vested interests.

"We cannot sit back and continue to allow innocent people to lose their lives. This is the time for significant interested parties to show leadership when it comes to Syria."

Foreign Affairs Minster Murray McCully held out hope that the Security Council could still come up with a resolution on Syria in coming days - one that would acknowledge the collective will for a ceasefire to hold.

ABDALRHMAN ISMAIL/REUTERS A man carries an injured child after airstrikes in al-Qaterji, Aleppo.

'MAKE OR BREAK MOMENT'

The UN talks began with a speech by Secretary General Ban Ki-moon saying the humanitarian crisis "shames us all", and the collective failure to resolve the Syrian crisis "should haunt every member of this council".

Ban concluded his speech by saying "we are at a make-or-break moment."

UNITED NATIONS Prime Minister John Key chaired the United Nations Security Council meeting.

Key agreed, and he didn't mince words in his criticism of the lack of meaningful international assistance to end Syria's years-long conflict, which has displaced millions of people.

He condemned an attack on Monday on a humanitarian convoy. The US had blamed Russia, which denied responsibility.

The Syrian war was "the most devastating conflict of the 21st century", and Syria had become "a byword for failure" - for which Key slammed UN member states.

ABDALRHMAN ISMAIL/REUTERS A medic runs with a stretcher after airstrikes on the rebel-held al-Qaterji neighbourhood of Aleppo, Syria.

It was, he said, a "failure of the parties and their supporters to put peace, and the lives of innocent people ahead of self-interest and zero-sum politics".

"Failure to respond to the crisis early to prevent this tragedy. And a collective political failure, including by this Council, to do what must be done to end the conflict."

He said the UN must seize Wednesday's meeting as a path to peace.

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"Let's be clear: no one will benefit from a continuation of this conflict. The Syrian government, which bears responsibility for starting this war, cannot win. Nor can the many others whose support is allowing the conflict to continue.

"Ultimately, Syrians must reach agreement on their future government. But at this point it is clear that Syrians by themselves cannot end this war."

KEY'S PLEA TO THE UN

LUCAS JACKSON/REUTERS Heads of state and their representatives take part in the United Nations Security Council meeting.

Key said the problem was not a lack of direction - a UN resolution had set out the required steps, and established a timeline, but that was never implemented.

"Today, we all need to commit to restoring the cessation of hostilities, delivering aid to those who need it, and restarting political talks."

He urged Russia and the United States to continue talks over timeframe for a ceasefire.

LUCAS JACKSON/REUTERS Russian Foreign Minister Sergei Lavrov hit out at the United States in his speech at the United Nations Security Council meeting.

"The next few days will be critical in restoring the cessation of hostilities and getting humanitarian aid flowing. We urge the Syrian parties to abide by the arrangement. This council should unite to back those efforts."

He said the political solution needed to both address the causes of the conflict, and establish a new form of inclusive government.

"And it must provide more than just cosmetic change with regard to the central question of President Assad's future," Key said.

LUCAS JACKSON/REUTERS US Secretary of State John Kerry fired back at Russia in his speech.

He urged the US, Russia, Iran, Saudi Arabia and Turkey to work together on a ceasefire over the coming days.

"Advancing a political solution must be the priority in the weeks ahead. The people of Syria deserve this much."

"Longer term, we will need to hold to account those most responsible for the appalling atrocities we have witnessed. This includes those responsible for chemical weapons attacks."

EDUARDO MUNOZ/REUTERS Prime Minister John Key used his earlier address to the UN General Assembly to blast the Security Council's inaction on Syria, before chairing the UNSC meeting.

RUSSIA HITS OUT

Russian Foreign Minister Sergey Lavrov told the council there had been repeated violations of the cease fire agreed by the United States and Russia.

He referred to agreements between the US and Russia relating to the delivery of humanitarian aid, which asked that government and opposition forces be withdrawn at an equal distance from the road along which aid was delivered.

Syrian Government forces had began withdrawing their forces in accordance with the ceasefire agreement "only to see the opposition did not act similarly but started shelling government forces".

"The opposition forces have still not withdrawn their units from the Costello road in accordance with the September 9 agreements."

Lavrov said a list of 300 breaches had been conveyed to the US by "a whole number of opposition groups" including those who had supposedly signed up to the ceasefire.

This list was based "not on reports on the internet or through the media but obtained on the ground by a Russian military monitoring group so this information is based on concrete examples."

The breaches included shellings, mortar attacks and home made rocket launches.

Lavrov also referred to Russia's complaint that the bombing of Syrian Government troops by US-led coalition forces - which the US said was a mistake - had cleared the way for an assault by Islamic State forces.

"These kinds of coincidences require serious analysis and investigation."

Lavrov said Russia was similarly insisting on a "thorough investigation" into the aid convoy

He said Russia had provided all the information on hand including "real time video" of the actual event.

Lavrov said Russia remained committed to a negotiated pathway forward but condemned "preconditions" sought as part of that process.

USA BITES BACK

In a strongly-worded response, US Secretary of State John Kerry said Lavrov's speech made him feel like they were in a "parallel universe".

"He said that nobody should have any preconditions to come to the table. We met in Vienna twice. met here in New York and embraced the UN Security Council resolution.

"We met again in Munich and in each place, the International Syria Support Group and security council embraced a cease fire, applicable to all parties.

"That's not a precondition, that's an international agreement, four times arrived at. Four times countries have said we will do this. and four times it's been shredded by independent actors, by spoilers who don't want a ceasefire.

"How can people go sit at a table with a regime that bombs hospitals and drops chlorine gas again and again and again and again and acts with impunity.

"ou're supposed to sit there and have happy talk in Geneva ... when you've signed up to a cease fire and you don't adhere to it? What kind of credibility do you have with any of your people?"

Kerry referred to the attack on an aid convoy, and also pointed the finger at Syrian and Russian forces over an air strike that killed five medical workers.

"We cannot resolve this crisis if the major parties who come to the party ... are unwilling to do what's necessary to avoid escalation."

Kerry also acknowledged the coalition led airstrike on Syrian soldiers and said America owned up to its mistake.

"The coalition did hit people on Saturday. we did it, a terrible accident and within moments of it happening we acknowledged it. We didn't put out a bunch of obfuscating facts."

Kerry called for an immediate move to ground all aircraft flying over key humanitarian supply routes to "de-escalate the situation and give us a chance for humanitarian assistance to flow unimpeded".

That would help restore confidence and demonstrate a will to move to an immediate ceasefire, he said.

NZ'S ROLE IN THE TALKS

The talks are the centrepiece of New Zealand's final month presiding over the United Nations Security Council, and the most important day of our two-year term.

New Zealand has convened the world's most powerful leaders to talk Syria, in arguably what is one of the most crucial periods in the protracted five-year conflict.

As recently as last week the meeting was viewed as an opportunity for the Council to endorse a hard-fought agreement between Russia and the US for a ceasefire.

But successive strikes, reportedly from both sides, have killed both Syrian government forces and UN aid workers - seriously compromising the integrity of the truce and derailing already-fragile diplomatic relations.

All UN aid deliveries have been halted.

Key is leading the high-level meeting, which includes heads of Government and both US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov.

Will he be able to achieve progress toward peace and humanitarian support for the 275,000 Syrians living in besieged areas?

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