Image caption Dominique Strauss-Kahn arrived at court with his wife Anne Sinclair (left) in a six-car motorcade

Former IMF director Dominique Strauss-Kahn has arrived at a New York court, where a judge is expected to drop a sexual assault case against him.

Prosecutors have told the judge they were no longer convinced of his guilt beyond a reasonable doubt.

The case, based on a claim by hotel maid Nafissatou Diallo, has crumbled in recent weeks over questions about her credibility and motives.

Mr Strauss-Kahn, 62, was accused in May of attacking the African immigrant.

Ahead of a hearing scheduled for 11:30 local time (15:30 GMT), Mr Strauss-Kahn arrived at the court room in lower Manhattan in a six-car motorcade with his wife Anne Sinclair.

'Reliability undermined'

On Monday, prosecutors told the judge that Ms Diallo had "not been truthful on matters great and small", in a filing in New York state court.

An international media frenzy erupted on 14 May when Ms Diallo told police that Mr Strauss-Kahn had confronted her naked as she entered a suite at the Sofitel Hotel in New York City, chased her and forced her to perform oral sex.

If the case is dropped, Mr Strauss-Kahn would be free to return to France, though he still faces a civil lawsuit from his 32-year-old accuser.

Image caption Protesters gathered outside the court on Tuesday, denouncing the Manhattan district attorney

In the court filing, prosecutors laid out in detail the case they had assembled against Mr Strauss-Kahn - and their doubts.

"The physical, scientific and other evidence establishes that the defendant engaged in a hurried sexual encounter with the complainant, but it does not independently establish her claim of a forcible, non-consensual encounter," the filing said.

In addition, "evidence gathered during our post-indictment investigation severely undermined her reliability as a witness in this case".

Prosecutors said that if they were unable to believe Ms Diallo's story beyond a reasonable doubt, "we cannot ask a jury to do so".

Speaking to reporters after a brief meeting on Monday with prosecutors at the court in Manhattan, Ms Diallo's lawyer Kenneth Thompson said: "Manhattan District Attorney Cyrus Vance has denied the right of a woman to get justice in a rape case.

"He has not only turned his back on this innocent victim but he has also turned his back on the forensic, medical and other physical evidence in this case."

Mr Thompson filed a motion asking the judge to disqualify Mr Vance's office from the case and to appoint a special prosecutor, a move rejected on Tuesday morning by the judge.

'Financial motive'

Mr Strauss-Kahn's lawyers, meanwhile, said they had always "maintained that there were many reasons to believe that [his] accuser was not credible".

Media playback is unsupported on your device Media caption Ms Diallo's lawyer, Kenneth Thompson, says his client has been denied justice

"Mr Strauss-Kahn and his family are grateful that the district attorney's office took our concerns seriously and concluded on its own that this case cannot proceed further," William Taylor and Benjamin Brafman said in a statement.

The Frenchman was forced from his job as director of the International Monetary Fund after his arrest on board an Air France jet.

But within weeks, prosecutors said there were inconsistencies in Ms Diallo's accounts of the alleged assault and of her background.

It was revealed that she had been recorded discussing the case with a jailed friend and appeared to refer to Mr Strauss-Kahn's wealth, which his supporters said pointed to a financial motive.

Prosecutors also said Ms Diallo had not been truthful in tax documents, nor on an asylum application form in her account of a gang rape she said she suffered back in Guinea.

Mr Strauss-Kahn was later freed from his restrictive bail conditions.

Ms Diallo then took the unusual step of giving media interviews, defending her allegations against him.

On 8 August, she filed a civil suit against Mr Strauss-Kahn.

Authorities in Paris are still considering whether to press charges against him over an allegation by French writer Tristane Banon that he tried to rape her during a 2003 interview.

Mr Strauss-Kahn had been touted as a leading contender to take on French President Nicolas Sarkozy in the April 2012 presidential elections.