The latest UK-EU talks on post-Brexit trade have ended without “significant areas of progress”, EU chief negotiator Michel Barnier has said.
He added: “I don’t think we can go on like this forever.”
The UK has until the end of June to ask for the “transition period” – keeping it in the single market and customs union – to be extended into next year, but the government has ruled this out.
The talks come ahead of a “high-level” summit later this month.
The two sides have been critical of each other’s negotiation stance.
And businesses – hit by the coronavirus pandemic – have raised concerns over a possible “cliff-edge” break to the UK’s remaining access to the EU single market at the end of the year with no replacement deal.
Mr Barnier said he had to “speak the truth” about how negotiations – currently carried out online – were going, adding that they should “work better” when the sides meet in person, from later this month.
He accused the UK of “continuing to backtrack” on commitments it made in the Political Declaration signed with the EU, adding that it should be treated with “full respect”.
Downing Street has accused the EU of making a series of “unbalanced” demands binding the UK to EU laws and standards to an unprecedented degree for a trade deal.
The two sides are also in dispute over fisheries, with the UK resisting EU demands for continued long-term access to British waters.
UK chief negotiator David Frost has said he hopes a meeting later this month, at which both sides are due to review progress, could give “new impetus” to talks.
A date for the summit, expected to feature Prime Minister Boris Johnson and European Commission President Ursula von der Leyen, has not yet been fixed.
The UK left the EU on 31 January. The transition period lasts until 31 December and keeps the UK bound to most EU rules.
The sides currently have until then to reach a free-trade deal, needed if they want to do business without tariffs, quotas or other barriers in future.