Diallo has also filed a civil  lawsuit against former IMF chief Strauss-Kahn [Reuters]

Prosecutors in New York have filed papers recommending that all charges in the sex assault case against former International Monetary Fund chief Dominique Strauss-Kahn be dropped.

The testimony of a 32-year-old hotel maid from Guinea who accused Strauss-Kahn, 62, of sexual assault was not convincing beyond a reasonable doubt to present to a jury, prosecutors said in a court filing on Monday.

It said Nafissatou Diallo, the cleaner at New York's Sofitel Hotel who said Strauss-Kahn had forced her to perform oral sex on May 14 "has not been been truthful on matters great and small."

Diallo's lawyers said earlier on Monday that they would request a special prosecutor to pursue the criminal case, though legal experts said such a move would have little chance of succeeding.

"She should not have her right to go to trial in a criminal case taken away by the Manhattan district attorney's office," The New York Times quoted Kenneth Thompson, her lawyer, as saying.

Strauss-Kahn, who has denied the allegations, was the leading contender for the April 2012 French presidential elections until Diallo made the accusations against him.

He was arrested and forced to resign as head of the International Monetary Fund a few days later.

Strauss-Kahn still faces a civil lawsuit filed by Diallo on August 8 and a complaint from French writer Tristane Banon who said he tried to rape her during a 2003 interview. Authorities in Paris are considering whether to press charges in that case.

Credibility threatened

Diallo's credibility has teetered since late June when prosecutors disclosed that she made-up a story about being gang-raped for her US asylum application and allegedly lied about other aspects of her past.

That admission threatened her credibility as a witness, resulting in prosecutors releasing Strauss-Kahn from house arrest, though he remains barred from leaving the country.

Prosecutors also said that she also was not consistent about what she did after her encounter with Strauss-Kahn.

Furthermore, a law enforcement official said that she had alluded to Strauss-Kahn's wealth in a recorded phone conversation with a jailed friend, and her bank account had been a repository for tens of thousands of dollars she couldn't explain.

Diallo said the jailed man had used the bank account without telling her and Thompson, Diallo's lawyer, said that she mentioned Strauss-Kahn's money in the telephone call only to say that her alleged attacker was influential.

Thompson has acknowledged problems in her past but said her story about what happened in the hotel room never wavered - that Strauss-Kahn sexually assaulted her.

His defence lawyers have suggested any sexual encounter was consensual.