EU Council president Donald Tusk said “not enough progress” had been made to schedule a summit in November, adding to uncertainty over whether a Brexit deal could be reached before time runs out.
At the close of the EU Council summit, Theresa May said Brexit talks “were always going to be tough” and insisted a deal could still be reached.
But German Chancellor Angela Merkel warned that "each and everyone ought to prepare for a no deal” at the close of an EU gathering that had been earmarked as the decisive moment to reach a deal, but passed without progress.
“These were always going to be tough negotiations and they were always going to get tougher as we got to the closing stages,” Mrs May said in a press conference. “There are some difficult issues we are still working through.
"Crucial among those is this issue of the Northern Ireland backstop and ensuring that we can provide for a solution which is not the solution that was produced by the European Commission initially, which would have effectively carved Northern Ireland away from the rest of the United Kingdom.
"That is unacceptable to the UK Government. On that issue further solutions have been put forward.
"But what we want to do is to work to get through that so that we can actually get to the deal that I believe will be good for the British people."
European Commission president Jean Claude Juncker said an extension to the 21-month post-Brexit transition period “will probably happen” after the idea was floated during this week’s summit, risking further anger by Brexiteers in Mrs May’s party.
The Prime Minister sought to explain the proposal, saying: "What has now emerged is the idea that an option to extend the implementation period could be a further solution to this issue of the backstop in Northern Ireland,” she said.
“We are not doing is standing here proposing an extension to the implementation period."
“What we are doing is working to get solution on the backstop.”