Three Femen activists were acquitted of exhibitionism on Wednesday for a topless protest staged as former IMF chief Dominique Strauss-Kahn arrived at his trial for “aggravated pimping” in February 2015.

“It's the first acquittal in a trial against Femen on the charge of sexual exhibition,” their lawyer Valentine Reberioux told AFP.

“A political demonstration should not be confused with sexual aggression,” she said. “These are political acts using the nude torso as a mode of expression and it ends there.”

With slogans such as “pimps, clients, guilty” scrawled on their chests and hurling insults at the car, the three protesters were quickly rounded up by police as Strauss-Kahn's car entered an underground parking area near the court in Lille, northern France.

Strauss-Kahn, a former head of the International Monetary Fund, was accused of being at the centre of a large prostitution ring but was acquitted in June.

Prosecutors, who have 10 days to appeal Wednesday's verdict, had demanded a three-month suspended prison sentence and a €1,000 ($1,115) fine for the Femen activists.

The acquittal was the first for Femen in France after two convictions, which are under appeal.

One Femen activist was convicted and fined €1,500 for a topless protest against visiting Russian President Vladimir Putin in June 2014 at Paris's Grevin wax museum.

Another was given a one-month suspended prison sentence for a December 2013 topless protest outside the Madeleine church in Paris against harsh new restrictions on abortion in Spain.