Jeremy Corbyn will announce Labour’s support for remaining in a customs union with the EU after Brexit tomorrow, the party’s shadow Brexit spokesman can confirmed.
Sir Keir Starmer has said it was now "crunch time" for Theresa May over her approach to the customs union, and said it would be "better" to reach "bold" new trade agreements with other countries by working with the EU.
Mr Starmer said Labour had "long championed being in a customs union with the EU and the benefits".
READ MORE: Leonard faces soft-Brexit revolt as Corbyn rethinks
Speaking on the BBC’s Andrew Marr Show, he said: “Obviously it's the only way of realistically to get tariff free access, it's really important for our manufacturing base and nobody can answer the question how you keep your commitment to no hard border in Northern Ireland without a customs union."
It comes as Mr Corbyn’s own party heaped pressure on the Labour leader to go further and embrace continued membership of the single market.
In an open letter, 80 senior Labour figures called for a soft Brexit, including Frank McAveety and Cammy Day, the party’s group leaders in Glasgow and Edinburgh.
Scotland on Sunday revealed that ten of Scotland's 73 local parties are mounting a bid to force Scottish Labour leader Richard Leonard to adopt a pro-single market stance at the party’s conference in a fortnight.
And writing in Scotland on Sunday, Scottish Labour’s most senior MP Ian Murray warned both leaders that the party would “never be forgiven” if didn’t fight for a soft Brexit.
Yesterday Mr Starmer said Labour had had "many weeks of discussion unanimously" and had agreed to develop their policy, to be announced by Mr Corbyn in a speech on Monday.
He continued: "The customs arrangements at the moment are hardwired into the membership treaty so I think everybody now recognises there's going to have to be a new treaty - it will do the work of the customs union.”
Mr Starmer said Britain was more likely to strike new deals if it works "jointly with the EU", adding: "We all want to do bold new trade agreements but we would be better off doing that with the EU."
He also signalled support for cross-party amendments on the customs union to the Trade Bill.
READ MORE: Ian Murray: If we don’t back soft Brexit, Labour won’t be forgiven
"The majority of Parliament does not back her approach to a customs union and the majority in Parliament needs to be heard and it will be heard sooner rather than later,” Mr Starmer said.
International Trade Secretary Liam Fox urged Tory Remainers to keep an "open mind" after they threatened to rebel over the approach to membership of a customs union.
He suggested a meeting of the Brexit "war cabinet" last week had agreed proposals, which will be revealed in a speech by the Prime Minister on Friday, that would deal with their fears.
Former minister and leading Tory rebel Anna Soubry has warned she has cross-party support for a new amendment to the government's trade bill that would mandate the UK to form a customs union with Brussels after Brexit.
Asked if legislation was being delayed because the government would lose, Mr Fox replied: "We want to persuade our colleagues of the merits of our argument before we take the bill forward."
Mr Fox said the Government wanted to sign new international trade deals during the transition period that could be implemented afterwards, with work underway in partnership with 21 countries.
Tory former leader Iain Duncan Smith warned potential rebels against challenging the Government. He told the BBC's Sunday Politics: "I say to my colleagues, who might want to change some of this, just be very careful on this one because you're being invited into a Labour party tactical game which will actually end up in real damage to the UK."
Theresa May will hold a special Cabinet meeting on Thursday ahead of her keynote speech on Britain's exit from the EU in the North East the next day.
Labour MP Frank Field, who backed Leave, said remaining in a customs union or the single market would be a "deceit" and dismissed suggestions that Ms Soubry could defeat the government.
"It's all hype," Mr Field said. "The Government's got a majority on this. The idea Anna Soubry is going to lead all these people into the Labour lobby is just fairytales.”