Implied volatility gauges for sterling for overnight and one-week maturities jumped to over 17% and 14% respectively as traders braced for more currency market swings.
Updating the EU envoys from 0630 GMT, Barnier said the three most contentious issues in the negotiations have not yet been resolved, according to the diplomat, who was taking part in the closed-door briefing.
"We know that 100 percent access to fishing waters in the UK maritime zone is finished," European Affairs minister Clement Beaune told le Journal du Dimanche.
"We keep calm, as always, and if there is still a way, we will see," he told broadcasters in London as he entered the train station to head back to Brussels after talks were paused.
If the two sides fail to reach a deal, the five-year Brexit divorce will end messily just as Britain and Europe grapple with the vast economic cost of the COVID-19 outbreak.
An update on the latest in Brexit trade talks by EU negotiator Michel Barnier for national envoys to the bloc will not go ahead on Friday "due to the ongoing intensive negotiations in London".
"We are quickly approaching a make or break moment in the Brexit talks," Barnier told a video meeting of European envoys, a diplomat said, in an account of the video meeting confirmed by other sources.
The UK leaves Europe's trade and customs area in five weeks, but talks on a follow-on agreement are still stalled over fishing rights and fair trade rules.
Barnier was expected to go to London for more trade negotiators with his British counterpart, David Frost, as soon as later on Friday or over the weekend.
Britain abruptly froze the negotiations after EU leaders at a summit said it was up to Britain, not the EU, to make concessions, which London took as an affront.
Britain, which left the EU in January but remains bound by most of the bloc's rules until a transition period ends on December 31, accused Brussels of stalling negotiations.
"The European Council invites the Union?s chief negotiator to continue negotiations in the coming weeks, and calls on the UK to make the necessary moves to make an agreement possible,"
The two negotiators' teams are in fraught talks to reach a deal on the future relationship between the EU and Britain ahead of a meeting of the leaders of the 27-nation bloc next week.
Barnier made his comments as the EU and Britain were holding talks in Brussels on forging their future ties after four months of fruitless negotiations.
Britain left the EU, the world's largest trading bloc, on Jan. 31 after 47 years of partnership to the huge regret of EU leaders who now insist that London accept the economic consequences of looser ties.