Former IMF manager director Dominique Strauss-Kahn has been questioned by police in Lille for two days about his knowledge of a prostitution ring.
Mr Strauss-Kahn had to resign from the agency after he was accused of sexually assaulting a hotel maid in New York in May last year.
The ABC reports he has been questioned by police in the French city of Lille about a prostitution ring, and was released on Wednesday.
There are suggestions he could face charges relating to pimping and embezzlement.
Police want to know whether Mr Strauss-Kahn knew the women at sex parties he attended in Paris and Washington were prostitutes and how they were being paid.
But his lawyer, Henri Leclerc says he had no reason to know.
However, a magistrate is expected to summon him in the future, either as a witness or as a suspect.
Eight men have already been arrested as part of the Carlton inquiry, a hotel where clients were said to have been supplied with call-girls.
Investigators earlier interviewed prostitutes who said they had sex with Mr Strauss-Khan.