The private life of the former head of the International Monetary Fund is the subject of a reported new inquiry.

The French news agency and Reuters, both citing sources, say prosecutors have told Dominique Strauss-Kahn to appear before police for questioning about an illegal prostitution ring.

Officials say the ring supplied prostitutes for sex parties and for clubs in Paris and Washington. The sources say they want to know if Strauss-Kahn was aware that the women were prostitutes and whether he knew they were paid with fraudulently-obtained funds.

Officials say several businessmen and a police commissioner have already been arrested in connection with the probe.

Strauss-Kahn had been considered a leading candidate in this year's French presidential elections until his arrest last May over allegations he had raped a hotel maid. The charges were dropped but the maid, Nafissatou Diallo, is pursuing a civil case against the former IMF chief.

This past October, a French writer decided not to pursue a civil case against Strauss-Kahn. Tristane Banon made the decision after prosecutors dropped rape charges against Strauss-Khan.