The picture was hastily withdrawn after numerous complaints
France's justice minister has called for legal action to be taken against a man who was photographed wiping his bottom with the French flag.
Michele Alliot-Marie said it was unacceptable for the tricolour to be insulted in this way, and called for those responsible to be prosecuted.
Her response came after the photograph was displayed in a competition run by the media retailer, FNAC.
The image won a special mention in the "politically incorrect" category.
Taken on the street, the photograph shows a man seen from behind: his trousers are around his ankles and he is apparently wiping his bottom with a French flag.
The picture appeared last month in Metro, a free national newspaper, and was hastily withdrawn from the contest in the southern city of Nice after complaints from veterans' groups.
French law holds it is not an offence to insult the tricolour at a private event
"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 government got involved after being alerted by a local MP, says the BBC's Hugh Schofield in Paris.
But under French law, it is only an offence to insult the flag in an event organised by the public authorities - not in a private, cultural event such as this, adds our correspondent.
Ms Alliot-Marie said the law should be changed.
"Presumably the law has the legal means to punish such an intolerable act against the French flag," said the minister's spokesman.
"If the existing law proves incomplete in this regard, it should be revised."