EU negotiators have reportedly stepped up backroom Brexit talks with Labour amid concerns over Theresa May’s future.

The Prime Minister has faced repeated calls to resign since losing the Conservative majority in June, with fresh claims this week that more than 30 Tory MPs want her to stand down.

Uncertainty over Mrs May’s premiership has seen EU negotiators significantly increase the amount of talks held with Labour since the General Election, according to The Daily Telegraph.

The discussions have marked a significant change in tone towards Labour, and Brussels is seeking assurances from Jeremy Corbyn that he would honour agreements made with the Conservatives if he comes to power, it added.

Jeremy Corbyn and Theresa May In July, Mr Corbyn held very frank talks with EU chief negotiator Michel Barnier which lasted more than two hours.

Speaking ahead of the visit, Mr Corbyn said Labour was a government in waiting ready to take up the responsibility for Brexit negotiations.

Mrs May has insisted she has the “full support” of her ministers despite a claim from former Tory party chairman Grant Shapps that “one or two” Cabinet ministers agreed she should step down.

Only three Tory MPs have admitted to Sky News that they want Mrs May to resign immediately, with 100 others saying there should be no instant change to the leadership.

One current MP and former minister denied to Sky News that they were behind any plot, but added that the Prime Minister would find it very, very difficult to survive.

They said the image of her leaving Downing Street with tears in her eyes would have a profound effect on the party.

But they added there were probably many more than the 30 disaffected MPs allegedly held on a list by Mr Shapps, warning: I think the party is in a dreadful hole.

I think the damage that would be done to the party if she was forced out would be immense, and like many others I hope she herself will conclude that the best thing would be to go.

What Grant is saying is widely agreed with.

Another current MP and former minister who said Mrs May should step down told Sky News the writing is on the wall – I can’t see her going on.

Most MPs Sky News contacted said Mrs May should stay on for the good of party and country, praising her “grit” after a problem-plagued conference speech.

Some simply offered their full support and said they were 100% backing the PM.

Others have lined up to criticise Mr Shapps, who claimed a broad spread of MPs from across the party backed a leadership election.

Commons Leader Andrea Leadsom said the former party chairman should shut up, while colleague Nadine Dorries told Sky News he was plain wrong.