The UK Labour Party’s shadow Brexit secretary has warned that any cross-party deal on the UKs exit from the EU that does not include a confirmatory referendum would be unlikely to pass the House of Commons.

Keir Starmer said up to 150 of Labour's 229 MPs may refuse to vote for a deal if the government failed to promise a new poll.

He was speaking ahead of the next round of talks between the Labour and Conservative parties aimed at finding a way to break the Parliamentary impasse over Brexit in the UK.

"A significant number of Labour MPs, probably 120 if not 150, would not back a deal if it hasn't got a confirmatory vote,” he said in an interview with The Guardian.

"If the point of the exercise is to get a sustainable majority, over several weeks or months of delivering on the implementation, you can't leave a confirmatory vote out of the package.

"I've made it clear at this stage - at this 11th hour - any deal that comes through from this government ought to be subject to the lock of a confirmatory vote."

An anti-Brexit protestor outside the Houses of Parliament, London, 08-05-2019. Image: Victoria Jones/PA Wire/PA Images

Mr Starmer said it is “impossible to see” how a Parliamentary majority can be achieved with a confirmatory vote.

"It has got to be something truly deliverable,” he said.

"For many of my colleagues, they have made it clear that they will not vote for a deal without a confirmatory vote attached to it.”

Red lines

The talks have stalled in recent weeks with Labour accusing the UK Government or refusing to compromise on its red lines.

"Is the government actually prepared to change its red lines?” said Mr Starmer. “The answer is, so far, not really.”

"On substance, there is a considerable distance between us."

European Parliament election

The deadlock has seen a sharp dip in popularity for both parties in recent weeks – with a new poll this morning suggesting the Tories has slumped to fifth place ahead of the upcoming European Parliament elections.

The YouGov opinion poll for The Times puts Nigel Farage's Brexit Party in the lead on 34%.

Labour is on 16%, followed by the Liberal Democrats, the Greens and finally the Conservatives on just 10%.

Mr Starmer said Labour should not be afraid to call off the talks if they do not appear to moving towards an agreement.

"I think it would be wrong in principle to use up much more time simply exploring each other's positions,” he said.

"I do think we do probably in the coming days need to make that assessment."

He also warned that the upcoming Tory leadership battle is hampering the talks adding, “You don't normally seek to do a deal with someone about to leave office.”