"The UK should now indicate the way forward or indicate a plan," Barnier said. "More today than ever."

Barnier said Britain could still accept the stalled deal negotiated by May, reiterating it was "the only way" for Britain to leave the bloc in an orderly way.

If May cannot get her deal ratified by parliament then she has a choice between leaving without a deal, calling an election or asking the EU for a long delay to negotiate a Brexit deal with a much closer relationship with the bloc.

The third defeat of May's withdrawal agreement on Friday - the date the United Kingdom was originally scheduled to leave the EU - has left the weakest British leader in a generation facing a spiraling crisis.

Investors and diplomats are in despair at the chaos and such is the volatility of Brexit news from London that some traders have stepped away from sterling - which has seesawed on Brexit news since the 2016 referendum. Sterling fell on Tuesday.

The British electorate, its two major parties and May's cabinet are all divided over Brexit and May risks ripping her Conservative Party apart if she tilts towards a closer post-Brexit relationship with the EU or leaving without a deal.