Britain's deal for leaving the European Union must be worse than the terms of its membership, said Maltese Prime Minister Joseph Muscat, whose country has just taken on the six-month EU presidency.
"We want a fair deal for the United Kingdom but that fair deal has to be inferior to membership," Muscat told a press conference in Valletta with European Commission President Jean-Claude Juncker.
"We can see no situation where whatever is negotiated ends up being better than the current situation that the United Kingdom has."
Britain voted to leave the EU in a referendum in June last year but has yet to start formal negotiations with the other 27 countries on the terms of its departure and its future relationship.
British Prime Minister Theresa May has said she will trigger the official two-year divorce process by the end of March.
EU nations have warned Britain it cannot expect to keep all the benefits of membership of the single market while being able to limit the bloc's signature freedom of movement for people.
Muscat rejected suggestions that Britain may be able to play on divisions within the other 27 countries to extract concessions, saying that the rest of the EU was unusually unified.
"I have rarely been at a discussion on any other subject where the 27 member states have basically the same position," said the premier, whose country is a former British colony that also holds the rotating presidency of the Commonwealth.
"So I can't peek into the future and see whether one country or another will break that sort of unity, but I simply don't see it happening now."
The EU 27 are due to hold a special summit in Valletta in February to discuss the post-Brexit future followed by a major summit in Rome in March to mark the 60th anniversary of the Treaty of Rome which founded the EU's forerunner.
Juncker insisted that Brexit did not spell the end for the troubled EU, already beset by the biggest migration crisis in the continent's history and systemic problems with the euro currency.
"If we are considering the Brexit case as the beginning of the end we will make a major mistake," Juncker said.
"The Rome summit will bring together the best energies of the European nations."