Former Brexit negotiator Michel Barnier has said Britain can rejoin the EU anytime it wants.
He said the UK knew “exactly” what the conditions for rejoining the bloc were and that “the door is open”.
However, he could not resist a sideswipe at his nemesis, the former British PM Boris Johnson.
He accused the former Prime Minister of “disrespecting” the deal he signed.
He said: “The point is not to sign a treaty; the point is to respect the treaty and to respect its own signature.
“I never understood, I do not still understand, how the prime minister of such a country, a great country like the UK, can be able not to respect his own signature.”
Brussels was enraged by Mr Johnson’s breaking of commitments he signed up to in the Brexit deal – especially over the Northern Ireland border.
Mr Barnier accused Mr Johnson of creating “two lost years” when it came to the EU-UK relationship by dragging the UK into a legal battle over the Northern Ireland protocol.
But he said the EU had changed and that the UK could return any time.
He said: “The door is open any time.
“I always say that during the negotiation and after negotiation, the door remains open.
“To be clear, the UK government, the current government, the next government knows exactly what are the terms and conditions to be part of the single market to be part of the customs union to join the EU.”