A photograph of a man wiping his bottom with the French flag prompted the government on Wednesday to demand criminal proceedings against the artist that produced it.

The image, one of the winners in a photo contest organised by the book and record shop FNAC in the southern city of Nice, sparked a controversy after it appeared last month in a free national newspaper, Metro.

Justice Minister Michele Alliot-Marie "has demanded that criminal proceedings be launched against this unacceptable act," said justice ministry spokesman Guillaume Didier.

"Presumably the law has the legal means to punish such an intolerable act against the French flag," he added. "If the existing law proves incomplete in this regard, it should be revised."

The decision was made after the ministry received a letter from Eric Ciotti, a deputy from President Nicolas Sarkozy's UMP party and president of the Alpes-Maritime region, who deemed the image "offensive" and called for an investigation.

"I want the person who committed this outrage to be punished, and possibly those who published it," he wrote in his letter, adding that he had received numerous complaints from war veterans and other shocked constituents.

The state prosecutor in Nice, Eric de Mongolfier, told AFP he had examined the case last month at the ministry's request and ruled the photograph did not constitute an offence since it was done in a "creative spirit".

FNAC said it had quickly taken measures to counter the controversy.

"As soon as we saw that people were shocked by the image, we withdrew it from the list of winners, with the photographer's consent, and we have not exhibited it," said a FNAC spokeswoman.

The newspaper defended itself saying it had merely "covered a local event" that it "did not sponsor".

"It is a question of knowing what the limits of art, provocation and freedom of speech are," Metro France's chief editor Frederic Vezard told AFP.

Under France's penal code, insulting the French national anthem or the tricolor flag during a publicly organised event is punishable by up to six months' imprisonment and a fine of 7,500 euros (10,045 dollars)

Mongolfier said that to make it an offence, "the insult must be committed during an event organised or regulated by the public authorities, which is not the case" with the offending photograph.