The disgraced former IMF chief, Dominique Strauss-Kahn looks likely to face trial in France for "aggravated pimping" despite a ruling by prosecutors that the case should be dropped.

Magistrates investigating the so-called Carlton Affair - allegations of hotel orgies with prostitutes in France, Belgium and the United States - decided today to overrule the state prosecutor and send Mr Strauss-Kahn for trial.

Both the prosecution and Mr Strauss-Kahn, 64, can appeal against the ruling. If they fail, the former IMF chief and French finance minister will finally face a trial for sexual misconduct after a series of failed prosecutions or out-of-court settlements in other cases.

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DSK is one of 13 people, including a senior police officer and two businessmen, who were sent for trial yesterday for "aggravated pimping as part of a group" for their alleged part in organising hotel orgies. A more serious accusation of "conspiracy" was dropped.

Under French law "pimping" can mean any action, paid or unpaid, which assists an act of prostitution. It is not suggested that Mr Strauss-Kahn was paid but that he helped to organise the parties with a series of telephone text messages.

Frédérique Baulieu, one of DSK lawyers, said yesterday that her client had committed no offence. She accused the investigating magistrates of trying to enforce their own "moral" judgements, rather than the letter of the law.

It is unusual, but not unprecedented, for investigating magistrates to overrule the decision of the state prosecutor. The former President Jacques Chirac was convicted in 2011 on corruption charges which the prosecutor had wanted to drop. The investigating magistrates insisted that the trial should go ahead.

The "Carlton affair", named after a hotel in Lille in northern France, is the only criminal accusation remaining against Mr Strauss-Kahn. Charges that he sexually assaulted a hotel chamber-maid in New York two years ago came to nothing. He settled a civil action by the maid out of court.