PARIS (AFP) - President Francois Hollande on Tuesday backed attempts to ban a controversial French comedian as a furore intensified over his sketches widely condemned as anti-Semitic.

Weighing into a debate that has gripped France, Mr Hollande urged local officials to apply an interior ministry circular authorising city mayors or police chiefs to cancel performances of the comic, Dieudonne M'Bala M'Bala, on public order grounds.

Several cities and towns, among them Nantes and Bordeaux, have declared prohibitions on shows the comedian, who goes by his first name, was to have staged. Officials claimed there was a risk of violent clashes between fans and protesters.

Mr Hollande said the interior ministry instructions were to "ensure that no one can use a performance for the goals of provocation and the promotion of overtly anti-Semitic theories".

The Socialist leader said local officials had to be "vigilant and inflexible" in their response to what he described as "shameful provocation", without specifically mentioning Dieudonne.

But the bans are expected to face legal challenges on freedom of speech grounds. Dieudonne's tour was to have started on Thursday in Nantes and run until June.

He appears to be guaranteed an audience in Switzerland at least, where he is due to play for 10 nights in a 460-seat venue in the small town of Nyon.

Local official Olivier Mayor told AFP that Dieudonne could not be banned because of a precedent set when Geneva tried to ban him several years ago with a decision that was overturned by a judge.

"You can't convict someone in advance, we live by the rule of law," Mayor said.

Attempts to ban Dieudonne have also sparked misgivings amongst some opponents of the comic in France, who fear that such moves only fuel his popularity further with his target audience and enhance his opportunities to cash in on his notoriety.

Dieudonne, 47, is the son of a father from Cameroon and a white French mother. He has been performing anti-Semitic material for years but gained greater prominence in recent months as a result of the Internet-driven success of the "quenelle", his trademark arm gesture which some have described as a reverse Nazi salute.

Footballer Nicolas Anelka, a former member of France's national team, stirred up a row by performing the gesture during a goal celebration for his English club West Brom last month.

Defenders of the comic say the gesture is simply a coded "up yours" directed at the French establishment and thousands of ordinary French people have used it without being aware of any racist overtones.

The gesture has taken on sinister connotations, however, with the publication of pictures of Dieudonne fans performing quenelles outside synagogues, at a holocaust museum and in front of the school in Toulouse where in 2012 an Islamist gunman killed a rabbi and three Jewish children.

Sold-out shows

Dieudonne's popularity - more than 5,000 tickets have been sold for the opening night of his tour - has exacerbated concern over a perceived resurgence of anti-Semitism in France under the guise of a brand of anti-Zionism.

In Tours, where all 2,000 tickets for a Dieudonne appearance on Friday have been sold, the mayor, Jean Germain, said a new generation had to understand that the comic's attacks on Jews could not be tolerated.

"We have to be able to say to the young that shouting 'death to the Jews' is forbidden," Germain said. "That is not freedom of speech." Coming in the wake of a series of incidents last year in which the country's most prominent black politician, Justice Minister Christiane Taubira, was subjected to monkey taunts, concerns have risen that overt racism is becoming dangerously acceptable in France.

The trend has been linked by some to the rising electoral popularity of the anti-immigration, anti-EU National Front (FN), founded by Jean-Marie Le Pen, who is the godfather to one of Dieudonne's children.

Le Pen's daughter, Marine, who succeeded him as party leader, says she is as shocked as anyone else by the comic's anti-Semitism, but believes the government is wrong to try and ban him.

"A preemptive ban would have shaky legal foundations and uncertain political results," Ms Marine Le Pen said Tuesday.

She added that she believed there was a sort of "personal vendetta" by Interior Minister Manuel Valls against the comedian.

That prompted Anne Hidalgo, a member of Hollande's Socialist Party running to become Paris's next mayor, to tell TV channel iTele that the National Front was fully behind Dieudonne.

"You can see clearly that the National Front hasn't changed. It's a far-right party and in the heart of the far right there is always the anti-Semite dimension very present," Ms Hidalgo said.