Labour should back Theresa May's Brexit deal if it includes a backstop plan which keeps the UK in a customs union, one of the party's MPs said last night.

Lisa Nandy said Labour MPs 'owe it to the country' to find a way to secure a Brexit deal rather than letting Britain crash out of the Brussels bloc.

The Prime Minister is said to have nearly reached a secret agreement with the EU as she frantically tries to get a deal approved before the end of the year.

It would reportedly keep the whole of the UK in a customs union with the EU - avoiding a hard Irish border.

The PM may have to rely on Labour votes to get her deal through Parliament as she is already facing a backbench mutiny over the plan, which Boris Johnson branded a 'stinker'.

Ms Nandy, Labour MP for Wigan, said Labour politicians should consider backing the PM's deal if it protects the economy and saves jobs.

Lisa Nandy said that Labour MPs (pictured at Labour's party conference in Brighton) 'owe it to the country' to find a way to secure a Brexit deal rather than letting Britain crash out of the Brussels bloc with no deal

She told the BBC Radio 4 Westminster Hour: 'All MPs owe it to the country to try and find a way through this and look at whichever deal comes back with an open mind about what is in the best interests of our constituents.'

She added: 'Having a UK-wide customs arrangement … would be a really big piece of the jigsaw for Labour, and something that we ought to consider.'

A number of Labour MPs, including Caroline Flint, have suggested they would back the PM's deal if it is a choice between that and crashing out with no agreement at all.

What is the final issue in the Brexit talks? Theresa May insists the Brexit deal is 95 per cent done - but the final issue of the Irish border backstop may be the hardest part. The backstop sets out what will happen to the Irish border if the Brexit transition ends before a final UK-EU trade deal is in place. Transition is currently due to end in December 2020. The EU is still insisting that in the absence of a full trade deal, Northern Ireland should stay in the EU customs union while the rest of the UK leaves to ensure the Irish border remains open. Mrs May has flatly rejected the idea, saying she would not agree to anything that risked splitting the UK. Instead, the government has mooted a temporary customs union for the whole UK. There would also probably need to be more regulatory checks between mainland UK and Northern Ireland to protect the single market. Some already take place, but they could be dramatically stepped up - potentially creating a huge flashpoint with the DUP. Brussels now appears to be prepared to do a UK-wide backstop in the divorce deal - but insists it must be robust and the UK could not exit it unilaterally. Advertisement

And the PM has made several public attempts too woo Labour MPs - imploring them to back her plan in the country's national interest.

But Ms Nandy took a swipe at Mrs May - accusing Number Ten of failing to build a cross-party coalition in Parliament for her Brexit plan.

She said: 'The trouble is still, that although there appears to be a bit of progress made between the UK and the EU Theresa May’s biggest problems are in her own party.

‘She is still being held to ransom by a small group of hard Brexiteers who don’t want a future trading relationship with the EU, or at least on very limited terms.

‘And she has not even begun to start thinking about how she does the hard work in Parliament to understand how she would build a majority to get this deal through.

‘And with less than 150 days to go until we leave, either with that Withdrawal Agreement or with no deal, I think this is getting really serious.’

Westminster is swirling with reports that No10 is on the brink of doing a deal with the EU which it could announce this week.

It would see the UK staying a customs union with the EU to avoid a hard Irish border - the major stumbling block which has threatened to derail the talks.

Downing Street has dismissed rumours the arrangement could last for years, and tried to play down reports a deal is effectively in place.

But Brexit Secretary Dominic Raab is said to be demanding that the UK is able to leave unilaterally within three months if he backstop does kick in - and the idea of extra regulatory checks between Northern Ireland and the rest of the UK could cause a meltdown with Mrs May's DUP allies.

Former foreign secretary Boris Johnson (pictured left at Tory party conference in Birmingham last month) has criticised Prime Minister Theresa May (pictured, right , in Downing Street last week after rumours of a secret Brexit deal were leaked

The continuing tensions were laid bare today when Irish deputy PM Simon Coveney insisted that there cannot be a 'time limit' on any backstop, and the UK must not be able to end it unilaterally.

His message was retweeted by EU negotiator Sabine Weyand as Brussels ratcheted up pressure on Mrs May.

Mr Johnson said the plan was an 'absolute stinker' and a 'Christmas present of the finest old Brussels fudge' which meant 'we are proposing to hand over an amazing £40billion for absolutely nothing in return'.

'We have agreed to remain in vassalage forever,' he said.

'Even after we leave — according to this so-called deal — we will remain in a nonsensical 'implementation period' in which we will be effectively nonvoting members of the EU.

'For the first time in a thousand years we will have to accept foreign made laws — with no power to change or make those laws. We will be a vassal state — a colony — for at least 18 months, probably more.'