A judicial official says French investigators are studying accusations that Dominique Strauss-Kahn was involved in a rape in a Washington hotel in 2010.
Strauss-Kahn, via his lawyers, said Friday that he denies any violence.
An official at the prosecutor's office in the northern city of Lille said that investigating judges want to broaden their probe into a suspected prostitution ring to examine the rape claim.
Strauss-Kahn was handed preliminary charges for alleged aggravated pimping in the prostitution probe.
The official was not authorized to be publicly named because of prosecutor's office policy.
French daily Liberation said the accusation came from two Belgian prostitutes questioned in the prostitution probe.