CROSS-PARTY talks aimed at breaking the Brexit impasse appear to have collapsed, as Theresa May fights to keep her deal alive to prolong her premiership.

Chances of the Prime Minister receiving Labour support for the Withdrawal Agreement Bill (WAB) seem to have evaporated, with Jeremy Corbyn telling May that the cross-party Brexit talks have "gone as far as they can" and "we have been unable to bridge important policy gaps between us".

The parties' negotiating teams have been holding talks over the last six weeks but there has not been a breakthrough.

May will set out the timetable for her departure in early June after a crucial Commons vote on the agreement she thrashed out with the European Union, with defeat likely to hasten her exit from Number 10.

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Corbyn also said the prospect of a change in Tory leadership meant the Government was becoming "ever more unstable and its authority eroded" and Labour could not be confident in any cross-party agreement being delivered.

In a letter to May, Corbyn said: "I believe the talks between us about finding a compromise agreement on leaving the European Union have now gone as far as they can."

He added: "While there are some areas where compromise has been possible, we have been unable to bridge important policy gaps between us.

"Even more crucially, the increasing weakness and instability of your government means there cannot be confidence in securing whatever might be agreed between us."

As recently as Thursday night, Number 10 insisted the talks process remained alive.

There were meetings between officials on Thursday and the prospect of the talks collapsing was "not how I see it", a senior source said.

Labour's Hilary Benn, chairman of the Brexit Select Committee, said there was little point in continuing the cross-party talks if they were going nowhere.

"It doesn't come as a great surprise to me because over the six weeks they've been going it doesn't appear that much progress has been made," he told BBC Radio 4's Today programme.

"If there's not going to be any progress then there wouldn't be much point in carrying on."

Meanwhile, Tory former Cabinet minister Nicky Morgan warned that aligning with the Brexit Party would be the "death knell" for the Conservatives.

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Elsewhere European Commission president has spoken of his regret at not speaking out during the campaign about Vote Leave's campaign claim that the UK sends the EU £350 million a week.

The National: Theresa May is meeting European Commission president Jean-Claude Juncker 

"If there's not going to be any progress then there wouldn't be much point in carrying on."

In an interview with Austrian paper Der Standard, he said: "I think it is an incomprehensible error on my part that I did not intervene in the Brexit campaign owing to British wishes.

"So many lies were told, so many of the consequences of a 'no' were misrepresented, we as a commission should have spoken up."

The Prime Minister will meet the chairman of the Tory backbench 1922 Committee Sir Graham Brady at the start of June to agree to the details of the leadership contest to succeed her.

The move follows a lengthy meeting on Thursday between May and the 18-strong 1922 executive during which she again came under pressure to name her exit date from Downing Street.

Even as the summit was taking place in Westminster, former foreign secretary Boris Johnson confirmed he would be a candidate to succeed the Prime Minister.

May and Sir Graham's next meeting will come after the WAB has received a second reading vote in the Commons in the week beginning June 3.