As former IMF boss, Dominique Strauss Kahn, arrived in court in Lille earlier, to answer charges for pimping, three topless protesters from the Femen activist group jumped on his car, with “pimps, clients, guilty” painted on their chests.
The protesters were taken away by police.
The former IMF chief – widely known by his initials DSK – is expected to give evidence for three days. He has not attended the trial since it opened on 2 February, when his appearance attracted international media attention.
The day before he was due to testify, an ex-prostitute named Mounia described how she had been paid €900 (£690) by a businessman, David Roquet, for what she had been told would be a “small party”.
She told the court that she had been specifically chosen for Mr Strauss-Kahn and no-one else.
Mounia’s evidence is expected to play an important part in the trial, as the prosecution tries to prove that he knew she and another woman, Jade, were prostitutes.
DSK is one of 13 co-accused, amongst whom are luxury hotel managers, a lawyer, a former police commissioner and a brothel owner nicknamed “Dodo the Pimp”.
They face charges of “aggravated pimping” while the former head of the International Monetary Fund is accused of using his business contacts to hire women for sex parties in Paris, Lille and Washington.
It is the latest sex-related allegation to trouble Mr Strauss-Kahn, who stepped down from the IMF after being accused of attempted rape by a hotel maid in New York in 2011.