Dominique Strauss-Kahn, the former head of the International Monetary Fund, will go on trial in Lille on Monday accused of pimping, in a case that threatens to expose the double life of the politician once tipped to be the next president of France.

The court is expected to hear how, while in Washington holding the most senior economic job in the world, Strauss-Kahn had group sex with prostitutes brought to him in Europe and the US, organised by French businessmen friends who wanted to curry favour with the man they thought would one day lead the country.

Details from court papers filed by the investigative magistrates and reported by several French papers referenced more than 15 “soirées” between 2009 and 2011 in which Strauss-Kahn was described as the instigator and “king of the party”, and where he allegedly had multiple encounters with numerous women in scenes described by some witnesses as “carnage” or “slaughter”.

The judges who referred the case to court argued that it was impossible for Strauss-Kahn to be unaware the woman were paid. They said that the encounters were organised around his busy international schedule, that he was the instigator and principal beneficiary and that the type of sexual practices involved and the lack of use of condoms suggested the women participating could only have been paid.

The encounters, involving sex workers from France and Belgium, took place in Brussels, Paris and three in Washington and New York. The prosecution claim that two entrepreneurs from northern France flew women to the US for orgies involving Strauss-Kahn while he was at the IMF, picking up the bill themselves.

Their last visit ended on 13 May, the day before Strauss-Kahn was arrested in New York over the alleged attempted rape of a hotel maid, Nafissatou Diallo. Criminal charges against Strauss-Kahn in the Diallo case were dropped by prosecutors, and he later settled a civil action with her.

That case marked the end of his political career in France. He currently acts as a consultant, including to the Serbian government and the Russian Regional Development Bank.

Strauss-Kahn has vehemently denied all charges of pimping, describing them as “dangerous and malicious insinuations and extrapolations”. At the time of the alleged offences, the former finance minister was tipped to be the next Socialist presidential candidate and was part of a celebrity power couple with his now-ex wife, the journalist Anne Sinclair.

He has admitted he took part in group sex but denied knowing that women at the orgies were prostitutes. “I challenge you to tell the difference between a naked prostitute and a naked woman of the world,” his lawyer, Henri Leclerc, said in 2011.

Some sex workers said they had been instructed not to mention they had been paid; others said it was impossible for him not to know. One sex worker, whose testimony to investigators was quoted in the Journal du Dimanche, said that as an “escort” it was rare to meet someone who displayed such a lack of respect as Strauss-Kahn.

The investigating magistrates said the case was not a moral crusade, arguing there were concrete indications that Strauss-Kahn was the “central pivot” of sexual encounters that favoured prostitution. Prostitution involving people over 18 is not illegal in France but pimping and living off the benefits of it is against the law.

The charge of proxénétisme aggravé, which translates as aggravated procuring for the purposes of prostitution, covers a wide range of crimes, including aiding, abetting, organising, encouraging or assisting in the prostitution of others. It is punishable by up to 10 years in prison. All 13 people in the dock with Strauss-Kahn, including small businessmen and a senior police chief, have denied the charges. The case will be heard by three judges but no jury.

The case, known as the Carlton Affair, began in 2011 as an investigation into an alleged prostitution network at the Hotel Carlton in Lille.

Strauss-Kahn was not involved in any alleged activity at that hotel, but his name was mentioned by sex workers in interviews with investigators and the inquiry was widened.

His high profile and the others in the dock with him have made the case one of the trials of the year. Those who will be in court with the former IMF leader include Dominique Alderweireld, a portly, cigar-chewing owner of hostess bars in Belgium who goes by the name Dodo the Pimp and said he had prepared for the case by getting his teeth whitened in Spain.