The French Foreign Ministry has announced plans to close up to 20 of its schools and embassies around the world on Friday, following concerns over a backlash against the publication of cartoons of the Prophet Mohammed in a French magazine.

The cartoons, published in the satirical magazine Charlie Hebdo, hit newsstands today and France is bracing for a hostile reaction.

There are concerns that the magazine may further anger Muslims, already outraged over an anti-Islamic film.

Demonstrations against the 'Innocence of Muslims' film have already claimed at least 30 lives in more than 20 countries.

The cartoon published in the magazine plays off the US-produced film which portrays the prophet as a fraud, a womaniser and a child molester.

The offices of Charlie Hebdo were fire-bombed last year after the magazine published an edition entitled 'Sharia Hebdo' describing it as 'guest edited' by the Prophet Mohammed.

Authorities in France, which has Europe's largest Muslim population, called for calm amid concerns about violent protests in an already febrile atmosphere.

The cartoons, many of which depict the Prophet Mohammed naked, were published in the magazine today.

The front cover of the publication features an Orthodox Jew pushing the turbaned figure of Mohammed in a wheelchair.

The magazine plays on the demonstrations and response to the anti-Islam film along with the row over the publication in France of topless photos of the Duchess of Cambridge.

One of the cartoonists, who uses the name Tignous, today defended the drawings.

"It's just a drawing," he said. "It's not a provocation."

CFCM, an umbrella group for French Muslims, issued a statement expressing "deep concern" over the caricatures and warning that "in a very tense context, it risks exacerbating tensions and provoking reactions."

It urged French Muslims to "not cede to provocation and ... express their indignation in peace via legal means."

The French Prime Minister Jean-Marc Ayrault, today said the organisers of a demonstration against the 'Innocence of Muslims' film planned for Saturday, would not receive police authorisation, saying: "There's no reason for us to let a conflict that doesn't concern France come into our country."

The decision follows an unauthorised protest at the US embassy in France last Saturday that drew around 150 protesters and saw a number of arrests.

In Paris riot police were deployed around the magazine's offices.

Foreign minister Laurent Fabius, speaking on France Inter radio, said the principle of freedom of expression "must not be infringed."

But he added: "Is it pertinent, intelligent, in this context to pour oil on the fire? The answer is no."

He said he had "sent instructions to all countries where this could pose problems. We are taking specific security measures."

The French Foreign Ministry has also issued new travel advice, urging French people in the Muslim world to exercise "the greatest vigilance," avoiding all public gatherings and "sensitive buildings".

The closure of embassies on Friday is an attempt to head off protests following Friday prayers, a traditional time for demonstrations in the Muslim world.