LABOUR will oppose Theresa May's Brexit Bill if her deal remains unchanged, Sir Keir Starmer has warned.

After Jeremy Corbyn’s spokesman declined to say whether Labour would oppose the Withdrawal Agreement Bill[WAB] – leaving open the possibility that the Opposition would abstain on the first Commons vote with a view to trying to amend the legislation at later stages – the Shadow Brexit Secretary made clear that without an agreed cross-party deal, Labour would oppose the bill because to do otherwise would put the "cart before the horse".

Sir Keir questioned whether the Prime Minister’s strategy was to put the legislation before MPs in the week beginning June 3 as a means of clinging onto power amid Tory moves to boot her out.

Steve Barclay, the Brexit Secretary during Commons question-time, told MPs the Government had been looking at whether changes could be made to the WAB to ensure it commanded a "wider body of support", adding it would be for them to decide to back the Bill.

He also reiterated no-deal Brexit planning was continuing ahead of the October 31 EU deadline and dismissed a second referendum on Mrs May's deal as a "bad idea".

Sir Keir pointed out how Mr Barclay had told the Commons in February that it was key to approve a Brexit deal ahead of the WAB and asked if a fourth meaningful vote would be held before the legislation was introduced next month.

"I'd have thought it was patently clear that if the Prime Minister's deal is put for a fourth time, if it's allowed, it will fail just as it has failed three times already,” declared the Shadow Secretary of State.

"But I want to make it clear that Labour opposes the idea of passing the WAB without an agreed deal; that would put the cart before the horse and Labour will vote against at Second Reading on that basis.”

He went on: "How on earth does the Secretary of State think that a Bill to implement a deal that isn't before the House can pass in two weeks' time? Or is this about keeping the Prime Minister in office for another week to give her a lifeline for today's meeting of the 1922 Committee?"

Mr Barclay replied: "It will be an issue for the House to decide when it sees that legislation whether it does command a majority of the House.

"It may be that his personal position is that it's irrelevant what's in that text because he personally wants a second referendum.

"That's not the basis on which the discussions have been held, that may be his personal position, it is not - as I understand it - the official position of the Leader of the Opposition.”

He added: "But it will be for the House to make a decision and what the Prime Minister has made clear is there'll be an opportunity to do that in the week after recess."

On a no-deal Brexit, Mr Barclay said: "Planning is continuing for no-deal. Funding is allocated and it is important that as a Government we use the time that we have between now and October 31 to ensure we are prepared should that eventuality arise. But it is in our interests to secure a deal so it becomes unnecessary."

Earlier, Labour’s Hilary Benn, who chairs the Commons Brexit Committee, questioned why MPs would be allowed four votes on the Brexit deal but the Government would not allow voters to have a second say.

Mr Barclay replied: "Because we had a decision; we gave the British public that and we have not delivered on that."

And he said he would have "much more time" for Mr Benn's position if he said he wanted to use a public vote to discuss the merits of different ways of exiting the EU.

Paul Blomfield, the Shadow Brexit Minister, also referenced a letter sent this week from senior Tories urging the Prime Minister to "reject a customs union solution with Labour" and asked whether Mr Barclay agreed.

The Brexit Secretary said: "My personal position has always been clear. We made a commitment in terms of the single market and customs union and that was clear in the manifesto."

Mr Blomfield responded: "We do deserve some clarity on these issues. The authors of the letter also said of any agreement that is reached: 'No leader can bind his or her successor, so the deal would likely be at best temporary, at worst illusory.' Do you agree with that?"

Mr Barclay said he supported leaving and had voted consistently. He said Labour had "refused" to stand by its own manifesto commitments.