French satirical paper Charlie Hebdo attack condemned
The French Prime Minister, Francois Fillon, has condemned a petrol-bomb attack on the offices of the satirical magazine Charlie Hebdo, which named the Prophet Muhammed as a "guest editor".
Mr Fillon said freedom of expression was an inalienable right in France and no cause could justify such violence.
The offices of the magazine, in Paris, were destroyed in the attack.
The government says everything possible will be done to find those responsible.
The front cover of Wednesday's Charlie Hebdo carried a caricature of the Prophet making a facetious comment.
It was described as a special edition on the Arab Spring, intended to "celebrate" the victory of an Islamist party in last month's Tunisian elections.
The editor-in-chief of the magazine, Stephane Charbonnier, said Islam could not be excluded from freedom of the press.
He said: "If we can poke fun at everything in France, if we can talk about anything in France apart from Islam or the consequences of Islamism, that is annoying."
Mr Charbonnier, also known as Charb, said he did not see the attack on the magazine as the work of French Muslims, but of what he called "idiot extremists".
Charb said the magazine had received several threats on Twitter and Facebook before the attack.
"This is the first time we have been physically attacked, but we won't let it get to us," he said.
Police said Charlie Hebdo's headquarters had been petrol-bombed in the early hours of Wednesday morning.
There was a serious blaze but nobody was injured.
The left-leaning daily newspaper, Liberation, has opened-up its offices for staff of the magazine to use.
Charlie Hebdo's website has also been hacked with a message in English and Turkish attacking the magazine.
The edition of the paper published on Wednesday was called Charia Hebdo - a play on the Islamic word sharia.
The cover shows Muhammad saying: "100 lashes if you are not dying of laughter".
Inside, there is an editorial, attributed to the Prophet Muhammad, and more cartoons - one showing the Prophet with a clown's red nose.
Depiction of the Prophet is strictly prohibited in Islam.
In a statement on Tuesday, the magazine said it was motivated by the recent victory of the Islamist Ennadha party in elections in Tunisia, and by indications that sharia law could form the basis of legislation in post-Gaddafi Libya.
The magazine denied it was trying to be provocative.
On Tuesday, Charb told the AFP news agency : "We don't feel like causing further provocation. We simply feel like doing our job as usual. The only difference this week is that Muhammad is on the cover and it's pretty rare to put him on the cover."
The head of the French Council of the Muslim Faith, Mohammed Moussaoui, joined politicians in condemning the attack.
In 2007, Charlie Hebdo reprinted 12 controversial cartoons of the Prophet Muhammad that were first shown in a Danish newspaper, Jyllands-Posten, and caused outrage in the Muslim world.
The magazine was sued for incitement to racism by two Islamic groups in France, but was acquitted by a Paris court.