Europe's top civil servant has said he is "not very optimistic" about Britain's chances of leaving the European Union with a deal.

European Commission President Jean-Claude Juncker met British Prime Minister Theresa May in Brussels on Wednesday evening but on Thursday morning warned a committee that he still "cannot exclude" a no-deal exit.

"My efforts are oriented in a way that the worst can be avoided. But I am not very optimistic when it comes to this issue," said Juncker.

"In the British parliament every time they are voting, there is a majority against something, there is no majority in favor of something," he told a session of the European Economic and Social Committee (EESC).

U.K. leader May has agreed a deal to exit the European Union with Brussels but has so far failed to gain the required support needed from U.K. lawmakers.

Describing Brexit as an act of "deconstruction," Juncker also warned that Britain's exit could have "terrible economic and social consequences" for both the U.K. and continental Europe.

Shortly after the comments, sterling dipped briefly before regaining ground. At around 11 a.m. GMT, sterling was trading 0.15 percent higher at $1.306.