Media playback is unsupported on your device Media caption Brexit: Boris Johnson defends 'go whistle' remark

Boris Johnson has been defending his much quoted jibe that the EU could "go whistle" over the Brexit bill.

The UK and EU are widely believed to have now agreed a deal which will see the UK paying up to 50bn euros (£44bn).

But the foreign secretary said he had been referring, in July, to reports the UK could face a 100bn euro bill.

He spoke as talks continue about the remaining sticking point in the initial phase of Brexit talks - what happens at the Northern Ireland border.

The foreign secretary said - at a question and answer session after a speech on global terrorism - that whatever was agreed must be "consistent with taking back control of our laws, of our borders and our cash".

His "go whistle" comment was made in a response in the House of Commons to Conservative backbencher Philip Hollobone:

Media playback is unsupported on your device Media caption Boris Johnson's message to the EU: "Go whistle seems to me to be an entirely appropriate expression"

Mr Johnson said he had been "teased" about it since, but at the time he had been "asked my reaction to some of the very extortionate sums that I had heard, in the region of £80bn or £100bn".

He said that on detailed examination of financial obligations "the British government is absolutely punctilious in wanting to meet our friends more than halfway and to be useful.

"The financial offer we are making is very good but it is nowhere near the sums that I was first invited to comment on, in a musical way."

Where are the Brexit talks at now?

The government says it is "optimistic" about finding a solution to the key sticking point - an agreement on the Irish border.

The government needs to get everyone onside on the issue in the coming days for Brexit negotiations to move forwards.

Media playback is unsupported on your device Media caption Chris Grayling: I'm optimistic about deal

The UK, which is due to leave the EU in March 2019, wants to open talks on a new free trade deal as soon as possible.

But the EU will only agree to this when enough progress has been made on the "separation issues" - the "divorce bill", expat citizens' rights and the Northern Ireland border - that have been the subject of negotiations so far.

So the UK is trying to settle the Northern Ireland border issue before EU leaders meet next week.

The sticking point explained

Media playback is unsupported on your device Media caption Arlene Foster claimed the Irish government prevented the DUP seeing the wording of the text

On Monday, the DUP - whose support Prime Minister Theresa May needs to win key votes at Westminster - objected to draft plans drawn up by the UK and the EU.

The DUP said the proposals, which aimed to avoid border checks by aligning regulations on both sides of the border between Northern Ireland and the Republic of Ireland, were not acceptable.

The party has said it will not accept any agreement in which Northern Ireland is treated differently from the rest of the UK.

The Republic of Ireland - which is an EU member - says it wants a guarantee that a hard border will not be put up after Brexit.

A European Commission spokesman said there was "no white smoke yet" on Brexit negotiations.

Can border checks be avoided?

Image copyright AFP/Getty Image caption Disagreements remain over how the Irish border should be treated after Brexit

With Brexit, the UK is leaving the EU's customs union - but Transport Secretary Chris Grayling said this did not mean there would need to be a physical border with people carrying out border checks.

Speaking on BBC Radio 4's Today programme, the transport secretary said people had misunderstood the key term "regulatory alignment" which has been the focus of the debate.

Some Eurosceptics who do not want to keep close ties to Brussels fear this could hamper the UK's ability to strike trade deals with other countries.

But Mr Grayling, a key Leave campaigner in the 2016 referendum, said: "We don't have to have, and we've never said we will, and we don't want, to have a situation where in future our laws are identical to the European Union.

"There will be areas where we do do things in a very similar way, there will be areas in which we don't do things in the a very similar way and that's all the PM was seeking to ensure - to make sure trade flows as freely as possible across the border."

He added: "I remain absolutely optimistic that we will reach a successful point, we will move on to the trade talks, because ultimately it is in everybody's interests for that to happen."

What is the deadline for a deal?

The BBC's Adam Fleming said that following an update from chief EU negotiator Michel Barnier on Wednesday, EU member states agreed there must be clarity within 48 hours for them to have enough time to consult with their capitals about draft guidelines for phase two of the talks.

At the 14-15 December summit, European leaders will decide whether enough progress has been made in the negotiations on Ireland, the UK's "divorce bill" and citizens' rights so far to open trade talks.

On Wednesday the Republic of Ireland's Prime Minister Leo Varadkar said he expected Theresa May to come up with a new wording aimed at satisfying all parties, adding: "I expressed my willingness to consider that."

A European Commission spokesman said on Thursday that things have to be sorted this week, adding: "Our week includes Sunday."

Not all Theresa May's MPs agree

As well as trying to appease the DUP, Dublin and Brussels, Theresa May also needs Conservative MPs to back whatever solution she puts forward.

But not all of them agree - and the pressure on the prime minister was underlined on Wednesday when 19 Tory MPs who back a "soft Brexit" wrote to her saying it was "highly irresponsible" for anyone to dictate terms which may scupper a deal.

This followed Eurosceptic MPs urging her to lay down new red lines before agreeing to hand over any money.

In the latest letter, the 19 MPs - who largely backed Remain in the 2016 referendum - say they support the PM's handling of the negotiations, in particular the "political and practical difficulties" relating to the Irish border.

But they hit out at what they say are attempts by some in their party to paint a no-deal scenario in which the UK failed to agree a trade agreement as "some status quo which the UK simply opts to adopt".

The MPs included former cabinet ministers Stephen Crabb, Dominic Grieve, Anna Soubry and Nicky Morgan.

Should Brexit be delayed?

That's the suggestion from a House of Lords committee, which says a "time-limited extension of the UK's EU membership" would "buy time" for a deal to be reached.

The committee doubts exit negotiations will be completed by the scheduled departure date of March 2019.

The UK is due to leave the EU at this point because Theresa May formally triggered a two-year countdown to Brexit in March 2017.

The government does not agree, and says it is confident negotiations can be completed by March 2019.

But the Lords committee says: "The overwhelming weight of evidence suggests that this will be impossible.

"If buying a bit more time means that we get a better outcome, which benefits businesses and citizens on both sides, a short extension of EU membership may be a price worth paying."