By Brian Love

PARIS (Reuters) - Former IMF chief Dominique Strauss-Kahn finds out on Wednesday whether the last sex offence case against him in France will be dropped, 18 months after rape accusations ended his presidential ambitions.

The 63-year-old has asked a court in northern France to halt a judicial inquiry to determine whether he should stand trial on pimping charges related to sex parties attended by him and by prostitutes.

Strauss-Kahn wants the inquiry abandoned on the grounds that the charge of suspected pimping is not backed up and that rules governing investigations were not respected, Richard Malka, one of his defense lawyers, said.

"We are requesting that this investigation be annulled on account of the fact that there are insufficient grounds to support it," Malka said.

An appeals court in the city of Douai, north of Paris, held a closed-door hearing a month ago and will tell the lawyers its decision on Wednesday.

Strauss-Kahn was about to enter the French presidential race when police escorted him off a plane minutes before takeoff from New York in mid-May 2011 to face charges, since dropped, that he tried to rape Sofitel hotel maid Nafissatou Diallo.

While U.S. prosecutors abandoned the criminal charges weeks later due to concern over witness credibility, Diallo launched civil proceedings and Strauss-Kahn's legal woes multiplied on return to his native France.

A female writer 30 years his junior filed an attempted rape complaint that was rejected by public prosecutors who said that there was evidence of sexual assault but that it was too late to pursue him on an incident dating back to 2003.

His name then cropped up in relation to the Carlton Affair, named after a hotel in northern France at the centre of police inquiries into sex parties where prostitutes and the then IMF chief took part, on occasion in Washington.

A group rape charge was dropped in the Carlton inquiry after a prostitute withdrew her allegation but investigators are still pursuing Strauss-Kahn on the grounds that his involvement in sex parties attended by prostitutes may be construed as pimping - a point Malka says does not stand up.

Strauss-Kahn's defense team has repeatedly argued that the former IMF chief did not know that women present as sex parties he attended were paid prostitutes and that using prostitutes is not itself an offence in France.

(Additional reporting by Thierry Leveque; editing by Jason Webb)