French prosecutors have widened an investigation into former IMF chief Dominique Strauss-Kahn's alleged participation in a prostitution ring.

Authorities said Monday that Lille police will open a preliminary inquiry into acts alleged to have taken place between 15 and 18 December 2010 in Washington D.C..

CNN was waiting to hear back from Strauss-Kahn's lawyers Monday morning.

The French newspaper Liberation reported earlier this month that the allegations stemmed from statements made by two women it describes as "escort girls," who were interviewed by Belgian police as part of an investigation into a prostitution ring run out of the Carlton Hotel in Lille, near France's border with Belgium.

According to the newspaper's account of the depositions, the women said they had accompanied two associates of Strauss-Kahn on a visit to Washington, where they had stayed at the W Hotel.

One of them alleged that Strauss-Kahn had used force against her during a sexual encounter at the hotel, despite her protests.

The newspaper did not specify how it obtained the statements. CNN could not independently confirm the report.