French interior minister and presidential candidate Nicolas Sarkozy has defended a weekly sued for printing cartoons of the Prophet Muhammad.
"Charlie Hebdo must be veiled!" says the cover of the magazine
Two French Muslim groups are suing Charlie Hebdo magazine for defamation over the cartoons, printed a year ago.
Mr Sarkozy's letter of support was read out in the Paris court hearing the case and prompted France's top Muslim body to call an urgent meeting in response.
Editor Philippe Val told the court the cartoons critiqued "ideas, not men".
The newspaper Liberation republished the cartoons on Wednesday in solidarity with the magazine.
The two-day trial is being seen as a test of the boundaries of free speech and religious sensitivities in France.
A lawyer for the magazine read a letter out from Mr Sarkozy, who is standing as presidential candidate for the right-wing UMP.
Mr Sarkozy noted he was often a target of the magazine but said he would prefer "too many caricatures to an absence of caricature".
Mr Sarkozy's letter drew concern from one of the Muslim groups behind the legal action.
"He should remain neutral," Abdullah Zekri of the Paris Grand Mosque was as saying quoted by Reuters news agency.
The official French Council of Muslim Faith (CFCM) voiced anger at what it said was government interference and convened an emergency meeting.
The Paris Mosque and the Union of Islamic Organisations of France (UOIF) say the magazine "insulted people on the basis of religion".
Muslims regard images of the Prophet Mohammed as blasphemous.
Speaking at the opening of the hearing, Mr Val asked: "If we no longer have the right to laugh at terrorists, what arms are citizens left with?"
"How is making fun of those who commit terrorist acts throwing oil on the fire?"
But the Muslim groups said Charlie Hebdo's decision to publish the cartoons "was part of a considered plan of provocation aimed against the Islamic community in its most intimate faith".
It was "born out of a simplistic Islamophobia as well as purely commercial interests".
"This is an attack on Muslims," UOIF President Lhaj Thami Breze told the court according to Reuters. "It is as if the Prophet taught terrorism to Muslims, and so all Muslims are terrorists."
The illustrations originally appeared in the best-selling Danish newspaper Jyllands-Posten on 30 September 2005 to accompany an editorial criticising self-censorship in the Danish media.
One image shows the Prophet Muhammad carrying a lit bomb in the shape of a turban on his head decorated with the Islamic creed.
Over the next few months they were reprinted in a number of French publications and elsewhere in Europe and around the world.
Reaction in the Muslim world built up in January and February of 2006 culminating in sometimes violent protests.
In republishing the cartoons, Liberation called the trial "idiotic", adding: "It is not words which wound, or pictures that kill. It is bombs."
In October, a Danish court rejected a libel case brought by several Muslim groups against the Jyllands-Posten.
The court in Aarhus said there was not enough reason to believe the cartoons were meant to be insulting or harmful.