Boris Johnson has been accused of engaging in “stupid blame game” after Downing Street claimed the EU had made a Brexit deal “impossible”.
Downing Street sources claimed German chancellor Angela Merkel had made clear that an agreement was now “overwhelmingly unlikely”.
Following a telephone call with Boris Johnson, she was said to have insisted the Irish must have a veto over Northern Ireland leaving the customs union.
The claims provoked a furious response from European Council president Donald Tusk who accused him of jeopardising the future security of the EU and the UK.
“Boris Johnson, what’s at stake is not winning some stupid blame game,” he tweeted.
“At stake is the future of Europe and the UK as well as the security and interests of our people.
“You don’t want a deal, you don’t want an extension, you don’t want to revoke, quo vadis?”
The Prime Minister’s official spokesman confirmed that there had been a “frank exchange” of views with the German chancellor, but refused to be drawn any further on the “source” claims.
Amid the dramatic escalation in the war of words between London and Brussels, there was apparent alarm among some UK ministers at the prospect the Government could withdraw security co-operation with the EU if it tries to stop the UK leaving in a no-deal Brexit at the end of the month.
Northern Ireland Secretary Julian Smith said: “I am clear that any threat on withdrawing security co-operation with Ireland is unacceptable.”
The Prime Minister’s spokesman insisted however that Mr Johnson had consistently made plain the UK continued to have “a close security partnership with our EU colleagues”.
The row comes after EU leaders made clear that Mr Johnson’s plan to resolve issue of the Northern Ireland backstop was not a basis for an agreement.
A no 10 source said Mrs Merkel had told the Prime Minister that the UK could not leave the EU without leaving Northern Ireland behind in a customs union with the EU.
“It was a very useful clarifying moment in all sorts of ways,” the unnamed source, quoted by Sky News, said.
“If this represents a new established position, then it means a deal is essentially impossible, not just now but ever.
“It also made clear that they are willing to torpedo the Good Friday Agreement.”
Their call followed an overnight briefing to The Spectator magazine from an unnamed No 10 source warning any attempt by the EU to prevent Britain leaving at the end of October would be treated as “hostile interference” in UK politics.
“We will make clear privately and publicly that countries which oppose delay will go the front of the queue for future co-operation – co-operation on things both within and outside EU competences” the source said.
“Those who support delay will go to the bottom of the queue. Supporting delay will be seen by this Government as hostile interference in domestic politics, and over half of the public will agree with us.”
The source also warned that negotiations with Brussels could collapse this week and blamed Irish premier Leo Varadkar for refusing to engage.
Former cabinet minister Amber Rudd, who quit the Government and the Tory Party over Brexit, said the Prime Minister’s chief adviser Dominic Cummings appeared to be behind the briefing.
“It reveals that there doesn’t appear to be an actual plan at all,” she told BBC Radio 4’s Today programme.
“Instead, what they’re doing is angrily, apparently, begging the EU not to support a delay which will be required because of the position that Parliament has taken.
“And I urgently would ask the Prime Minister to take control of this and give us some clarity and some dignity and diplomacy on what is taking place.”
Shadow Brexit secretary Sir Keir Starmer said the comments were a “cynical” attempt by No 10 to “sabotage” the negotiations.
“Boris Johnson will never take responsibility for his own failure to put forward a credible deal. His strategy from day one has been no-deal Brexit,” he said.
Irish deputy premier Simon Coveney said Mr Tusk’s statement reflected the “frustration” felt across the EU.
“We remain open to finalise a fair Brexit deal but need a UK Government willing to work with EU to get it done,” he tweeted.
However DUP leader Arlene Foster said Mrs Merkel’s reported comments showed the true objective of the EU and the Dublin was to permanently “trap” Northern Ireland in a customs union.
“For the United Kingdom to be asked to leave a part of its sovereign territory in a foreign organisation of which the UK would no longer be a part and over which we would have no say whatsoever is beyond crazy,” she said.
“No UK government could ever concede such a surrender.”
A European Commission spokeswoman said the EU’s position had not changed.
She told a briefing in Brussels: “We want a deal.
“We are working for a deal with the United Kingdom.
“And under no circumstances will we accept that the EU wants to do harm to the Good Friday Agreement.
“The purpose of our work is to protect it.”