A French court has postponed a decision on requests that it call off a sex offence inquiry where former IMF chief Dominique Strauss-Kahn risks trial on a charge of "aggravated pimping".

The court in Douai, a town north of Paris, had been scheduled to rule today on the last major inquiry the 63-year-old is fighting in France, but announced instead that it would deliver a verdict on 19 December.

"All we can do is wait patiently," said Richard Malka, a defence lawyer for Mr Strauss-Kahn.

"All we can say is this shows that the arguments are sufficiently serious to justify taking time to examine them."

Mr Strauss-Kahn was on the brink of entering the race for the 2012 French presidency when police in New York boarded his plane minutes before take-off in May last year and took him off to face allegations that he sexually assaulted hotel maid Nafissatou Diallo.

US prosecutors dropped criminal charges weeks later, prompting Ms Diallo to start civil proceedings, but his judicial woes multiplied on his return to his native France.

His name cropped up in relation to the so-called Carlton Affair, named after a Lille hotel at the centre of police inquiries into sex parties attended by prostitutes and the then International Monetary Fund chief, on occasion in Washington.

A group rape charge was dropped in the Carlton inquiry after a prostitute withdrew her allegation.

However, investigators are still pursuing Mr Strauss-Kahn on the grounds that his involvement in sex parties attended by prostitutes may be construed as pimping, a point his legal defence team says does not stand up.

Mr Strauss-Kahn's lawyers have repeatedly argued that he did not know that women present at sex parties he attended were paid prostitutes.

Public prosecutor Guillaume Maigret said nothing could be inferred from the court postponement, but it drew criticism from the lawyer of another man being investigated on the same count as Mr Strauss-Kahn - police commissioner Jean-Christophe Lagarde.

Mr Lagarde's lawyer Olivier Bluche said the request to postpone the inquiry had been lodged on 19 April, meaning that by the new court date the affair will have been weighing over his client for eight months.

"That's an extraordinarily long time for someone unjustifiably branded a suspect," he said.