Angela Merkel Sets Britain 30-Day Brexit Deadline

German Chancellor Angela Merkel has given Britain 30 days to come up with alternatives to the Irish border backstop to ensure a Brexit deal, but French President Emmanuel Macron cautioned there could be no new renegotiation.

More than three years after the UK voted to quit the EU, it is still unclear on what terms -- or indeed whether -- the bloc's second-largest economy will leave the club it joined in 1973.

British Prime Minister Boris Johnson is betting that the threat of no-deal Brexit turmoil will convince Merkel and Macron that the EU should do a last-minute deal to suit his demands.

Speaking beside Merkel at the German Chancellery in Berlin on Wednesday, Johnson repeatedly said that the Irish border backstop - the contingency plan aimed at preventing a hard border between the UK and Ireland - needed to be removed in full.

Photo: Hayoung Jeon via AAP

"It was said we will probably find a solution in two years. But we could also find one in the next 30 days, why not?" Merkel said.

Johnson confirmed she had given him 30 days to come up with alternatives and said there was ample scope for a deal. A British government source noted the more positive tone of Merkel's comments.

But just an hour after Merkel spoke, Macron said the demands made by Johnson for a renegotiation of the divorce deal, including the removal of the Irish backstop, were not workable as they currently stood.

Johnson is due to meet Macron in Paris on Thursday.

Asked about the distance between the positions of London and the other 27 members of the EU, Johnson was hopeful.

Boris Johnson. Image: Getty Images.

"If we approach this with sufficient patience and optimism, we can get this done. It's in the final furlong generally when the horses change places and the winning deal appears," he said.

But with just over 10 weeks left until the scheduled departure, the EU has repeatedly said it will not renegotiate the withdrawal agreement and that it will stand behind member state Ireland.

As Johnson arrived, protesters outside the Chancellery gates shouted "Stop Brexit".

Johnson and Merkel smiled and joked about the British premier's German language skills.

Merkel has previously promised to discuss "practical solutions" to the Irish border insurance policy or "backstop" that Johnson says is unacceptable - but she has said the withdrawal agreement would not be reopened.

The German leader has suggested solving the Irish border riddle as part of the declaration on post-Brexit ties - a possible way to avoid a no-deal Brexit.

But France believes a no-deal Brexit is now the most likely Brexit scenario, said an official in Macron's office who cautioned that Berlin and Paris were united.

"Have no doubt that the French and German positions - and elsewhere - are the same. There's not the thickness of a cigarette paper between us," the French official said.