The SNP’s Westminster leader has said that the Prime Minister needs to “fundamentally change her position” to end the Brexit deadlock.

Ian Blackford has written to Theresa May to say that it would be “completely unacceptable” for her to propose only “cosmetic changes” to her EU withdrawal plan after it suffered a crushing defeat on Tuesday.

Mr Blackford met with Mrs May as she held talks with other leaders after surviving a confidence vote on Wednesday, and said that he is willing to meet her again so long as the discussion focuses on three key points.

He said any future talks must see the UK Government focus on extending Article 50 to stop the clock on Brexit, bringing forward legislation for a second EU referendum and taking “no deal” off the table.

Theresa May Theresa May will make a statement to MPs on Monday setting out her position on Brexit (Stefan Rousseau/PA)

Mr Blackford said: “With the clock ticking it is concerning that there has been little indication so far that the Prime Minister understands the implications of the defeat she suffered last week and the steps that now need to be taken.

“It would be completely unacceptable for Theresa May to propose only cosmetic changes to a deal which has been so decisively rejected by Parliament.

“The Prime Minister has had two-and-a-half years to listen – she now has to show she is willing to engage with ideas and change her position.

“That’s why it is hugely concerning that media interviews given by Cabinet ministers, such as the Secretary of State for Scotland, seem to be closing down options instead of opening them up.”

The Prime Minister is spending the weekend at her official country retreat at Chequers working on a statement to MPs on Monday setting out her approach following the overwhelming rejection of her Brexit deal.

Mr Blackford said: “Pressing ahead with another proposal that is certain to be defeated would be reckless, waste more precious time and will lead to further economic damage and uncertainty.

“The Prime Minister needs to fundamentally change her position.”

A Downing Street source said: “The Prime Minister was clear at the start of cross-party talks that there are principles underpinning these talks.

“These principles are that we make a smooth and orderly transition. We need to reach a consensus around a deal that respects the result of the referendum.

“And it needs to be a consensus that can command a majority in the House of Commons.”