Chris Grayling warns customs union would leave Lithuania with 'more power' over Britain's trading relationship than UK ministers

Theresa May's Cabinet has descended into further conflict after Chris Grayling slammed the idea of the UK joining a customs union to break the ongoing deadlock over Europe.

The UK Transport Secretary said the move would leave the government of Lithuania with "more power" over Britain's trading relationship than UK ministers.

His intervention came just hours after his Cabinet colleague David Gauke warned the Prime Minister not to "ignore" Parliament if it opts to back a softer Brexit in Monday's fresh round of indicative votes.

And it came amid reports that Grayling is among a string of Brexiteer Cabinet ministers who would be willing to quit the Government if May crosses her longstanding customs union red line.

The Transport Secretary told the Telegraph: "Are we really going to accept the situation where the government of Lithuania has more power over our trading relationship with the Commonwealth than our government does? That is the reality of the customs union."

The Cabinet minister said it was a "myth" that entering a customs union with the EU would automatically solve the Irish border issue and warned those pushing the policy shift: "It is not going to come without strings attached - the idea that we just get a customs arrangement without having to sign up to a raft of single market legislation is extremely unlikely."

MPs will on Monday hold another round of so-called 'indicative votes' on alternatives to Theresa May's deal after last week failing to agree on a way forward.

Although no one option commanded a majority in last week’s vote, a plan for a permanent customs union with the EU came closest to doing so, and the Commons could try to legislate to force the Government's hand on its preferred proposal.

Justice Secretary Gauke told the BBC: “If Parliament is voting overwhelmingly against leaving the European Union without a deal, but is voting in favour of a softer Brexit, then I don't think it's sustainable to say, well, we'll ignore parliament's position and therefore leave without a deal.

“I don't think that is a sustainable position for the government to take."

While the Justice Secretary said he would “rather leave the customs union”, he urged his Tory colleagues to recognise that "my party does not have the votes to get its manifesto position through the House of Commons at the moment".

However, in a sign of the anger such a move could cause on the Conservative backbenches, Tory Brexiteer Anne-Marie Trevelyan on Sunday night reminded May of her longstanding opposition to membership of the customs union.

The European Research Group member told the BBC's Westminster Hour: "We cannot not deliver Brexit and the Prime Minister is right that a customs union will not deliver Brexit."