Downing Street has yet to respond to the leaked comments.
Short of a last-minute breakthrough, Johnson will have to decide whether to accept another delay or to go for a no-deal Brexit and get around a law demanding he extend.
It marked a change in rhetorical tone and provoked a furious response from Tusk, who accused the prime minister of jeopardising the future security of the European Union and the UK.
A frustrated Tusk accused Britain of playing with "the future of Europe and the UK" with no clear plan of what the country wanted.
"You don't want a deal, you don't want an extension, you don't want to revoke, quo vadis (where are you going)?"
Negotiations over a Brexit deal descended into further chaos Tuesday, with a United Kingdom government source telling the BBC that a deal was "essentially impossible" after a call between Boris Johnson and Angela Merkel went south over the question of Northern Ireland.
An array of remarks by unidentified British sources laid bare just how far apart the two sides are after three years of tortuous haggling over the first departure of a sovereign state from the EU.
The Irish government has said the plans are not the basis for a deal, and reports on Monday night suggested European Union chief negotiator Michel Barnier had briefed representatives of the 27 member states on a series of problems with the United Kingdom offer.
A handout photograph released by the UK Parliament shows opposition Labour Party shadow home secretary Diane Abbott (lower right) speaking at the despatch box during prime minister's questions in the House of Commons in London on October 2, 2019.
Anti-Brexit campaigners claimed victory after Scotland's highest court decided on Wednesday to wait before ruling whether to force Johnson to seek a delay to Britain's European Union divorce date if he has not struck a deal in the next 10 days.
On Oct. 17, Johnson is scheduled to travel to Brussels for a meeting of the European Council where he hopes a Brexit deal could be ratified.
'It also made clear that they are willing to torpedo the Good Friday Agreement'.
The EU considers, however, that the proposal contains some problematic points that must be clarified by the British government at the negotiating table before introducing any changes to the original withdrawal treaty. Furthermore, the deadline had not yet been reached, and so it would be inappropriate for the court to pass judgment at this time.
The Prime Minister must have found a deal by the end of October 17/18 to avoid a dilemma over the Benn Act, which compels him to ask Brussels for an extension if he can not get an agreement past MPs when he returns, a move he has ruled out taking.
But they admitted the court was likely to regard the government's promises as sufficient - "for the moment".
Unusually, Downing Street then provided a readout of what Merkel reportedly said, provoking an incendiary tweet from Tusk.
"Technical talks are continuing today so I don't see how talks could have actually broken down if they are happening today and in the days to continue", she said. We want a deal. "But if he doesn't, then we will face a genuine constitutional crisis and we will have to pick up the pieces then". Northern Ireland would continue to apply European Union legislation relating to agricultural and other products unless the Northern Ireland Assembly vetoes such a decision.