Macron, Johnson set for bruising Brexit talks in Paris

British Prime Minister Boris Johnson heads to Paris on Thursday for talks with French President Emmanuel Macron who is expected to rebuff his last-ditch efforts to renegotiate the UK's withdrawal from the European Union.

Macron, who has said previously he is happy to be the "bad guy" on Brexit, roundly rejected Johnson's calls to scrap a key plank of a deal negotiated between the EU and former British premier Theresa May.

"Renegotiation on the terms currently proposed by the British is not an option that exists, and that has always been made clear by (EU) President Tusk," Macron told reporters on Wednesday evening.

At stake is the so-called "backstop", an arrangement guaranteeing that border checks will not return between EU member Ireland and Northern Ireland which is part of Britain.

Johnson considers the backstop to be "anti-democratic" and an affront to British sovereignty because it will require London to keep its regulations aligned with the EU during a transition exit period.

The EU argues this is necessary to avoid the re-emergence of border checkpoints which could lead to a return of fighting on the divided island where anti-British violence has claimed thousands of lives.

More evidence of deadlock on Thursday would raise the chances of a "no deal" Brexit, which France now sees as the most likely scenario despite the expectation that it will wreak economic damage on Britain and the EU.

"The EU and member states need to take the possibility of a 'no deal' outcome much more seriously than before," a senior EU official told reporters in Brussels on Thursday on condition of anonymity.

The Paris visit is the second leg of Johnson's first foreign trip since he became prime minister a month ago.

On Wednesday, he told German Chancellor Angela Merkel in Berlin that the backstop has "grave defects for a sovereign, democratic country like the UK" and insisted the provision "has to go".

Merkel appeared to offer a glimmer of hope by saying Britain should try to find a breakthrough to the issue over the next month.

In the search for a solution, "maybe we can do it in the next 30 days, why not? Then we are one step further in the right direction," she said.

Johnson said he welcomed her "very blistering timetable".

Britain's eurosceptic press interpreted the exchange positively, with The Daily Mail saying "Boris Johnson received a Brexit boost last night".

"Can we do it? Ja, we can!" read its front page.

But the remarks fit a pattern in which Merkel has often been more conciliatory in public about Brexit than Macron, whose abrasive remarks have sometimes caused anger in London.

"There is not the width of cigarette paper between Paris and Berlin on these issues," a senior aide to Macron said on Wednesday on condition of anonymity.

The EU official in Brussels added that the EU was "a little concerned based on what we heard yesterday (in Berlin)."