Berlin: Dubbed a liar by his French counterpart and lampooned as a "political jester" in European newspapers, chief Brexit campaigner Boris Johnson faced a wave of criticism and mockery Thursday after being named Britain's foreign minister.

In a shock move, new Prime Minister Theresa May on Wednesday appointed the eccentric former London mayor, known for his gaffes and buffoonery, as the top diplomat to lead the country out of the EU.

French Foreign Minister Jean-Marc Ayrault said that as a "Leave" campaigner Johnson had "lied a lot" and said his appointment "reveals the British political crisis" following the referendum.

Ayrault claimed he was not worried about working with Johnson but stressed the need for a "clear, credible and reliable" negotiating partner.

The outspoken European Parliament chief Martin Schulz also slammed May's new cabinet, saying it was based on solving internal party splits rather than the national interest.

"The United Kingdom has to break this dangerously vicious cycle which has direct impacts on the rest of Europe," Schulz said.

There is widespread animosity in Europe toward Johnson who recently compared the EU's aims to those of Adolf Hitler.

After the Brexit vote, European Commission chief Jean-Claude Juncker labelled Johnson and other Leave campaigners "sad heroes".

German Foreign Minister Frank-Walter Steinmeier had said a day earlier he was outraged by Britain's "irresponsible politicians who first lured the country into Brexit, then... got out, refused to take responsibility, and went off to go and play cricket".

A senior German Social Democrat, Ralf Stegner, said an undiplomatic Johnson would now "negotiate the Brexit. Bon Voyage!"

The party's Rolf Muetzenich said he wouldn't be surprised if, next, "Britain appoints Dracula as health secretary".

- 'King of Blunder' -

Many governments, in line with protocol, congratulated their new counterpart, who will make his diplomatic debut in Brussels next week.

US Secretary of State John Kerry called Johnson, and both "agreed that the US-UK special relationship is as essential as ever", said the State Department.

Kerry "stressed US support for a sensible and measured approach to the Brexit process and offered to stay engaged as the UK government develops its plans", added spokesman John Kirby.

The foreign ministers of Canada, Norway, Latvia and Estonia also said they looked forward to meeting Johnson.

In Russia, Kremlin spokesman Dmitry Peskov voiced hopes that "the weightiness of his current position, of course, will certainly prompt a somewhat different rhetoric of a more diplomatic nature".

Many newspapers and social media users, however, treated the appointment as the latest act in a political theatre of the absurd.

Germany's Handelsblatt called Johnson a "political jester", the daily Sueddeutsche labelled his appointment an example of "British humour", while the French L'Obs news magazine's headline was simply "King of the Blunder".

Germany's Die Welt said many initially thought the "bombshell" appointment was a joke.

"The fact that Theresa May is... appointing, of all people, this undiplomatic, unpredictable and disloyal hotshot as foreign minister seems absurd at first glance," it said.

But it also saw the move as calculated, arguing that "the pressure now rests upon him -- and his undoubted ambition -- to prove himself".

- 'Ambitions, power plays' -

Germany news magazine Der Spiegel, in an online commentary headlined "House of Cards in Britain", was withering.

"Those who thought the shamelessness with which Britain's political class play their power games could not be surpassed were disabused of that notion yesterday," it said.

"Boris Johnson, King of Brexit, has now been rewarded with the post of foreign secretary, having initially stuck his head in the sand after the vote.

"Now, finally, there can be no more doubt that British politics is not concerned with the country's welfare, but with haggling for positions, personal ambitions and power plays."

In an article from London, Der Spiegel said Johnson "himself seemed surprised", having been widely regarded as "Britain's greatest bogeyman" after the vote.

But it also said May had appointed him "to heal the party and to show the voters... that she takes the referendum outcome seriously".

France's Liberation reminded its readers that Johnson "has never held a ministerial post and a few days ago he pathetically withdrew from the race to lead the Tory Party".

On social media, French writers let rip too, with one tweeting "a clown as the new foreign minister -- comedy or Shakespearean tragedy?" while another proposed that Johnson "recruit Mr Bean as an adviser".

AFP