EU negotiator Michel Barnier still hopes the UK can exit the European Union in an orderly fashion.
Mr Barnier said in an interview with FranceInfo radio that "I think we can save this accord" but that it was up to Britain to take responsibility.
Mr Barnier said: "It's not correct to say that a no-deal is the most probable" outcome.
"It's a possibility. It's not yet a probability."
If British politicians agree to seek a extension of the March 29 exit date, the 27 other countries in the EU must unanimously agree.
He said everyone must be sure that extending negotiations will not still lead to the impasse facing both sides.
He added that he sees no "added value" in Britain's departure, saying: "Brexit is lose-lose."