Labour ‘no-deal’ position

other MPs, states: “We are significantly concerned that your refusal to countenance planning for a ‘no deal’ will do material harm to Britain’s negotiating position in the discussions about our exit from the European Union.

“There are those in the EU for whom the sole priority in these negotiations is that they punish Britain: your policy would give them strength.”

Ms Fernandes said ruling out a no deal scenario deprived the UK of leverage in the withdrawal talks and amounted to a “betrayal of the national interest”.

Tory MP Philip Davies said Labour and the SNP’s position of ruling out a “no deal” scenario was “not a negotiation, it’s a capitulation”.

In the Commons, Mrs May agreed with him, adding: “You don’t enter negotiations by taking the stance that the Labour Party and the SNP have taken, because ... their rejection of a ‘no deal’ means that they will accept a deal at any price to the British taxpayer, whatever the damage that will do to our economy and we will not do that.”

The Prime Minister told the SNP’s Westminster leader Ian Blackford it would be “irresponsible” not to prepare for the prospect of failing to agree an acceptable deal.

Her comments came after Home Secretary Amber Rudd told MPs on Tuesday it would be “unthinkable” for the UK to break away from the EU without a deal, at least on security cooperation.

But Mrs May said: “What we are doing is working for the best possible deal for the UK. But it would be irresponsible of Government not to prepare for all possible scenarios.”