Boris Johnson’s Brexit stance was criticised as “unacceptable” by Michel Barnier shortly after the Prime Minister called for the EU to rethink its opposition to a new deal.

Brussels’ chief Brexit negotiator described Mr Johnson’s first Commons statement as Prime Minister as “rather combative”, in a message to member states on Thursday.

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The new Tory leader told MPs that Theresa May’s thrice-rejected deal was “unacceptable” and that the “abolition” of the Irish backstop to prevent a hard border was essential.

Boris Johnson making his Commons statementPrime Minister Boris Johnson addressed Parliament for the first time in the top job (UK Parliament/Jessica Taylor/PA)

But the EU insisted that the Withdrawal Agreement was the “best and only” deal possible.

Mr Barnier responded tersely to the Prime Minister’s speech in a message sent to member states and widely circulated in Brussels media.

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“PM Johnson has stated that if an agreement is to be reached it goes by way of eliminating the backstop. This is of course unacceptable and not within the mandate of the European Council,” Mr Barnier wrote.

The negotiator said Brussels would analyse any solutions compatible with the existing Withdrawal Agreement and reaffirmed a commitment to rework the Political Declaration.

“But as suggested by his rather combative speech, we have to be ready for a situation where he gives priority to the planning for ‘no deal’, partly to heap pressure on the unity of the EU27,” he wrote.

“I note also the many strong reactions to the speech in the House of Commons. In this context we must follow carefully the further political and economic reactions and developments in the UK following the speech.”

The Herald:

In a phone call with Mr Johnson, European Commission president Jean-Claude Juncker reiterated the EU’s position that the Withdrawal Agreement was “the best and only agreement possible”.

He repeated Brussels’ offer to make changes to the Political Declaration setting out the aims for the future relationship “and to analyse any ideas put forward by the United Kingdom, providing that they are compatible with the Withdrawal Agreement”.

The Prime Minister had expressed confidence in the Commons that he could obtain a fresh agreement by the October 31 deadline and said his predecessor’s deal could not be brought back for a vote again.

“Its terms are unacceptable to this Parliament and this country,” he said.

And Mr Johnson ruled out any tinkering being able to save the backstop, the emergency measure to prevent a hard border on the island of Ireland in the event of a no-deal.

“A time limit is not enough, if an agreement is to be reached it must be clearly understood that the way to the deal goes by way of the abolition of the backstop,” he said.

Mr Johnson also pledged with “absolute certainty” that the 3.2 million EU nationals in the UK would keep their rights to work and remain.

Downing Street would not respond directly to Mr Barnier’s leaked comments.

But the Prime Minister’s official spokesman said: “It’s day one, the Prime Minister has said he wants a deal and is going to be energetic in the pursuit of that.

“The fact remains, however, that the Withdrawal Agreement has been rejected three times by this Parliament and is clearly not acceptable to the current UK Parliament.”