Four prostitutes and one associate in a high-profile French prostitution trial have dropped their allegations against Dominique Strauss-Kahn, saying that there isn't enough proof that the former IMF chief violated the law.

Dominique Strauss-Kahn is accused of 'aggravated pimping'

The move on Monday increases the chances that , who was tipped as a potential candidate in the 2012 French presidential election before being accused of sexual assault in May 2011, will be acquitted of charges of "aggravated pimping".

Strauss-Kahn, 65, has admitted to while he was “saving the world” from the financial crisis while head of the International Monetary Fund (IMF), to being “rough” with his sexual “conquests” and to needing sex with exceptional frequency.

Strauss-Kahn, one of 14 people on trial, is accused of procuring prostitutes, which is a criminal offence in France.

But little evidence was heard that he had committed the offence of “aggravated pimping” during the prostitution trial in Lille, northern France.

He has insisted throughout the trial that he had no idea that women involved in these sex parties -- which took place in France, Washington and Brussels while he was leading the IMF -- were prostitutes.

One association, called Nid (Nest), a Catholic charity that provides welfare for prostitutes while calling for a total abolition of the trade, said it would maintain its accusations against Strauss-Kahn.

Court officials said lawyers maintained accusations against 13 other co-defendants in the trial in the northern French city of Lille.

‘Deviant sexual practices’

The case against Strauss-Kahn and his co-defendants dates from 2008 to 2011.

He openly told the court that while he was a “libertine” who enjoys group sex, it would have been too risky, as head of the IMF and preparing to run for the French presidency, to pay for sex and hope to get away with it.

But the trial has exposed Strauss-Kahn’s sometimes brutal sexual mores, with one witness, a self-confessed prostitute named only as “Jade”, claiming he sodomised her without permission during a threesome in a Brussels hotel.

At the end of the second day of his testimony last week, at one moment over the persistent questioning of his sexual preferences, calling the need for these details “absurd”.

He was not on trial, he said, for “deviant sexual practices”.

Fall from grace

Strauss-Kahn and his co-defendants have been giving evidence in the so-called "Carlton Affair" trial, named after the Lille hotel where alleged prostitution and pimping sparked the investigation into a sex ring involving Strauss-Kahn.

Strauss-Kahn, who was French finance minister in the 1990s and went on to head the IMF from 2007, was widely expected to run for -- and win -- the French presidency in the 2012 election against conservative incumbent Nicolas Sarkozy.

He was forced to withdraw following the damaging allegations that he had hotel maid Nafissatou Diallo at the Sofitel New York Hotel in May 2011.

Criminal charges against him were eventually dropped -- by which time the political damage was irreversible -- and Strauss-Kahn settled civil proceedings brought against him by Diallo in New York.