German Chancellor Angela Merkel has challenged Britain to come up with alternatives to the Irish border backstop within 30 days, after the UK made repeated calls to ditch the backstop from any Brexit deal during a state visit to Berlin.

Key points: Mr Johnson used the German phrase "Wir schaffen das" (we can manage this) in a taunt to Ms Merkel

Mr Johnson used the German phrase "Wir schaffen das" (we can manage this) in a taunt to Ms Merkel Mr Johnson confirmed Ms Merkel gave him 30 days to come up with alternatives to the backstop

Mr Johnson confirmed Ms Merkel gave him 30 days to come up with alternatives to the backstop France now believes no-deal Brexit is now the most-likely Brexit scenario

UK Prime Minister Boris Johnson, who is meeting European leaders this week to attempt to broker a new Brexit deal before the October 31 deadline, said the UK "wanted a deal" but could not accept the current solution for the thorny issue of the Irish border.

"We cannot accept the current withdrawal agreement arrangements that either divide the UK or lock us into the regulatory trading arrangements of the EU … without the UK having any say on those matters," he said at a joint press conference.

"But if we can do that [remove the backstop], then I'm absolutely certain that we can move forward together."

Speaking alongside Ms Merkel, the Conservative Party leader used a German phrase in his address that has brought Ms Merkel great pain in the recent past.

"Wir schaffen das" (we can manage this) was her response in 2015 when she was quizzed on whether Germany could absorb huge numbers of immigrants at the height of the migrant crisis.

It soon came into wider use for criticising Merkel's immigration policy. In 2016 she said she would not use the phrase again.

"We seek a deal and I believe that we can get one. We can do it, wir schaffen das, I think is the phrase," Mr Johnson said, which was met by laughter from the audience.

Ms Merkel and Mr Johnson met at the Chancellery in Berlin on Wednesday. ( AP: Michael Sohn )

Macron says British demands not workable

Ms Merkel said the backstop was "a placeholder that will no longer be necessary" if a solution to the impasse over the Irish border could be found.

"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?" Ms Merkel, Europe's most powerful leader, said.

Mr Johnson confirmed Ms Merkel had given him 30 days to come up with alternatives and said there was ample scope for a deal.

Just an hour after Ms Merkel spoke, French President Emmanuel Macron said the demands made by Mr Johnson for a renegotiation of the divorce deal, including the removal of the Irish backstop, were not workable as they currently stood.

French President Emmanuel Macron said the demands made by Mr Johnson for a renegotiation of the divorce deal were not workable. ( AP: Christophe Petit Tesson )

Speaking to reporters on Wednesday, Mr Macron said a no-deal Brexit would be of Britain's own making and not the European Union's, adding that any trade pact London cut with Washington would not mitigate the cost of leaving the bloc without a deal.

"Can the cost for Britain of a hard Brexit — because Britain will be the main victim — be offset by the United States of America? No. And even if it were a strategic choice, it would be at the cost of a historic vassalisation of Britain," he said.

Ms Merkel 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 now believes no-deal Brexit is now the most likely Brexit scenario, said an official in Mr 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.

"The idea of saying, 'There's not a deal, so I won't pay' does not work. We cannot imagine that a country like the UK would back out of an international commitment."

Once the nightmare scenario on the extreme edge of probability ranges, a 'no-deal' Brexit is now seen as a realistic possibility by both governments and investors.

Amid the political turmoil in London, little is clear. The alternatives are a delay, a last-minute deal, an election or even cancelling Brexit.

Mr Johnson is due to meet Mr Macron in Paris on Thursday.

ABC/wires