Camp sites in the Ardeche region had been told to step up security following Wednesday's attack on the girl that has been linked to a string of similar assaults at camp sites in recent weeks.

The 32-year-old suspect was arrested on Friday "without difficulty'' at his home in Privas, the capital of the Ardeche region, and taken into police custody, the public prosecutor in charge of the probe, Franck Alzingre, told AFP.

The man, "who comes from the centre of the Ardeche'', was "suspected of rape and sexual aggression against a minor'', Alzingre said, without making it clear whether the rape accusation concerned the little girl at the camp site.

Alzingre had said earlier that there was no evidence of a link between the latest attack and other incidents which have occurred on camp sites in the area since the end of June.

"At the moment we have not established a link between this week's attack and the other cases but we are not ruling out any avenue of investigation,'' he told reporters.

Although Alzingre played down suggestions a serial rapist could be operating in the region, he confirmed that a squad of 50 officers has been assigned to the case, far more than would normally work on a single crime.

The girl was attacked by a man in the early hours of Wednesday as she slept in a tent alongside her younger sister at a camp site in Saint-Didier-sous-Aubenas, in the south of the Ardeche.

Police had earlier said that as many as seven girls between the ages of seven and 12, one of whom was Dutch, had been attacked in the area in the past six weeks.