PARIS - Former International Monetary Fund (IMF) chief Dominique Strauss-Kahn, who was forced to quit his post over sexual assault in a New York hotel in 2011, reappeared on a French court over sex offences, including procuring of prostitutes.

On Monday, a trial in "Carlton Affair" opened in the northern city of Lille where the scandal-hit former French finance minister and 13 others were charged with "pimping with aggravating circumstances".

Those allegations have been dismissed by Strauss-Kahn, arguing he was a "libertine" who enjoys swinger parties but unaware that the women present were paid prostitutes and did not play any organizational role in an illegal prostitution ring.

However, investigating magistrates said Strauss-Kahn knew he was dealing with prostitutes when participating in sex parties in Paris, Lille and Washington from 2008 to 2011, local reports said.

If convicted in this three-week trial, Strauss-Kahn, 65, risks up to 10 years in jail and a fine of up to 1.5 million euros (about 1.7 million U.S. dollars).

The court rejected a prosecutor's request for the trial to be held behind closed doors to protect the identity of prostitutes who are due to testify about their encounters with Strauss-Kahn and other suspects, according to local reports.

Strauss-Kahn, who was considered a viable candidate to compete for the country's presidency in 2012, saw his political flying career ended after his May 2011 arrest in New York over rape accusations made by a Sofitel room-cleaner Naffisatou Diallo.

After charges were dropped, the ex-IMF boss returned home but kept a distance to France's political life, leaving the way open to Francois Hollande to win the race to the Elysee Palace three years ago.

An Odoxa poll for the daily Le Parisien issued on Sunday showed 79 percent of the 1,008 respondents believed Strauss-Kahn would have been a better president than Hollande.

"Not loved as a man but respected as a professional. The French think (Dominique Strauss-Khan) would have been better president than Francois Hollande and the economic and social situation of our country would be much better than it is today," Gael Slimane, Odoxa director wrote in a note.