A French judge was expected to prolong former IMF chief Dominique Strauss-Kahn's detention for questioning in a prostitution ring case, an inquiry source said on Tuesday.

The former IMF chief was detained earlier for questioning over allegations of "abetting aggravated pimping by an organised gang" and "misuse of company funds" and faced being held in cells overnight.

According to an official in the northern city of Lille, where the 62-year-old former statesman was being held in police station, an investigating magistrate was expected later Tuesday to permit an extended detention.

Such detentions for questioning are initially for 24 hours, but can be prolonged by a judge.