Boris Johnson has until the end of September to reveal his Brexit plans or else "it's over", according to the Finnish prime minister.
Antti Rinne is the current holder of the rotating EU Council presidency and said the Prime Minister had just 12 days to set out his plans for leaving.
Following a meeting with French president Emmanuel Macron, he said the EU needed a sign of progress.
“We both agreed that it is now time for Boris Johnson to produce his own proposals in writing - if they exist,” he said.
But Transport Secretary Grant Shapps has dismissed the September deadline, and told talkRADIO’s Julia Hartley-Brewer the government was instead looking towards October.
“In terms of deadlines actually there are two very clear deadlines. One is there is a European summit in the middle of October, not the end of September. The second is October 31 when we will be leaving Europe either way,” he said.
“The Prime Minister has been working extraordinarily hard on this and there are negotiations ongoing every single day of the week, so it’s disingenuous to suggest that there are not.”
Earlier in the week the European Commission president, Jean-Claude Juncker, said talks with Mr Johnson were “constructive” but he could not say “any real progress” had been made.
Brexit Secretary Stephen Barclay has urged the EU to show “flexibility” ahead of a meeting with chief Brexit negotiator Michel Barnier on Friday.
“A rigid approach now at this point is no way to progress a deal and the responsibility sits with both sides to find a solution,” he said.