Boris Johnson is a liar with his back to the wall, says French FM

Mr Ayrault said France needed a "credible and reliable" partner

France's foreign minister has said his newly appointed British counterpart, Boris Johnson, is a liar with "his back against the wall".

In comments to Europe 1 radio, Jean-Marc Ayrault said Mr Johnson had lied to the British people during the recent EU referendum campaign and would now be under pressure "to defend his country".

The former London mayor led the campaign to take Britain out of the EU.

He was booed at a reception at the French Embassy later on Thursday.

'Charming letter'

Mr Johnson was expected to stand for the Conservative party leadership in the wake of the referendum result, but did not put himself forward after key colleagues withdrew support.

His appointment as foreign secretary has surprised many politicians and commentators around the world, who have recalled his history of undiplomatic or offensive comments.

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Mr Ayrault said: "I am not at all worried about Boris Johnson, but you know his style, his method during the campaign - he lied a lot to the British people.

"[He has] his back against the wall to defend his country but also with his back against the wall the relationship with Europe should be clear.

"I need a partner with whom I can negotiate and who is clear, credible and reliable," he added.

"We cannot let this ambiguous, blurred situation drag on... in the interests of the British themselves."

Reacting to the comments, Mr Johnson said it was "inevitable there will be some plaster coming off the ceilings in the chancelleries of Europe. It was not the result they were expecting and they are making their views known in a frank and free way".

But he added: "The French foreign minister has in fact sent me a charming letter just a couple of hours ago saying how much he looked forward to working together and deepening Anglo-French co-operation in all sorts of areas, and that is what we want to achieve."

Mr Johnson said he wanted to reshape Britain's identity as a "great global player".

He said: "We have to give effect to the will of the people in the referendum but that does not mean leaving Europe. There is a massive difference between leaving the EU and our relations with Europe which, if anything, are going to be intensified."

But at a reception at the French Embassy in London later he was booed by some of those attending.

He had told them he wanted a "political, cultural, psychological and economic union between our countries at inter-governmental level. To coin a phrase 'toujours plus etroit [ever closer]'".

France and other EU states have urged Britain to start the process of leaving the EU promptly, to minimise uncertainty.

New Prime Minister Theresa May has promised to implement Britain's exit from the bloc but has not said when she plans to trigger the formal exit procedure.

She has already spoken to French President Francois Hollande. Mrs May's spokeswoman said she "explained that we would need some time to prepare for these negotiations".