It came minutes before Theresa May gave a speech saying she was "ambitious and positive" about negotiations but that there is still "some way to go".The Prime Minister claimed there were only "small issues" on citizens' rights left to resolve and insisted the key 'sufficient progress' motion needed to trigger phase-two talks was "within touching distance".She added the EU did "not need to be concerned" about its budget plan, which the UK signed up to until 2020."We will be going line by line through those commitments," she said.

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Despite Mr Tusk's announcement, the EU-27 have formally delayed a decision on progressing talks until another summit in December.

"Against this background, the European Council invites the Council (Art. 50) together with the Union negotiator to start internal preparatory discussions," a document released on Friday said.

Labour MP Heidi Alexander likened Mrs May to "a teenager trying to get away with handing in their homework late".

"It is nauseating to see ministers who told us that Brexit would be easy now trying to spin this failed summit as a success," she said.

"To have not made sufficient progress in negotiations 16 months after the referendum is an unambiguous failure."

Mrs May has left the summit, but the remaining European leaders are still locked in talks on subjects including the migration crisis and Catalonia.