EU leaders have warned the second crushing defeat of Theresa May’s Brexit deal has “significantly increased the likelihood" of the UK crashing out without an agreement.

Donald Tusk, president of the European Council, said his side had done “all that is possible to reach an agreement”.

He insisted the remaining 27 EU countries will only accept an extension to the Brexit deadline if there is a “credible justification” for doing so.

It came after Mrs May’s Brexit strategy was dealt another devastating blow, with MPs rejected her deal by an overwhelming majority for a second time.

The Withdrawal Agreement was defeated by 149 votes, reduced from the record 230-vote defeat of the first "meaningful vote" in January.

Mr Tusk said he regretted the result, adding: “Given the additional assurances provided by the EU in December, January and yesterday, it is difficult to see what more we can do.

“If there is a solution to the current impasse it can only be found in London.

“The EU for its part continues to stand by the Withdrawal Agreement, including the backstop, which serves to prevent a hard border in Ireland and preserve the integrity of the single market unless and until alternative arrangements can be found.

“With only 17 days left to 29 March, today's vote has significantly increased the likelihood of a no-deal Brexit.

“We will continue our no-deal preparations and ensure that we will be ready if such a scenario arises.

“Should there be a UK reasoned request for an extension, the EU27 will consider it and decide by unanimity.

“The EU27 will expect a credible justification for a possible extension and its duration.

“The smooth functioning of the EU institutions will need to be ensured.”

Michel Barnier, the EU’s chief negotiator, said it had done everything it could to help get the Withdrawal Agreement over the line.

He added: “The impasse can only be solved in the UK. Our no-deal preparations are now more important than ever before.”

MPs will vote on whether to rule out a no-deal Brexit tomorrow, but it will still remain the default option if nothing else is put in its place.

On Thursday, Westminster is set to vote on whether to ask the EU for an extension to the Article 50 process – pushing back the date of the UK’s exit.