French prosecutors dropped a sex assault probe into former IMF chief Dominique Strauss-Kahn yesterday, saying he admitted trying to kiss the alleged victim but the case was too old to prosecute.

Tristane Banon, a 32-year-old author, claims the politician tried to rape her in 2003, but prosecutors said evidence suggested sexual assault - which has a shorter statute of limitations - rather than attempted rape.

“Mr Strauss-Kahn admitted trying to kiss Ms Banon,” a judicial official told reporters. “He does not admit sexual assault, but that’s his opinion. The magistrate for his part said it could be regarded as a sexual assault.”

The Paris prosecutor’s office said in a statement: “Even if a prosecution for attempted rape could not be launched for lack of sufficient proof, facts that could be qualified as sexual assault were admitted.”

Henri Leclerc, one of Mr Strauss-Kahn’s lawyers, confirmed the details of the ruling, but insisted: “He admitted no violence of any kind. Mr Strauss-Kahn tried to kiss her. He was refused, and did not insist, allowing her to leave.”

Under French law sexual assault is a lesser charge than attempted rape and cannot be prosecuted if a complaint is made more than three years after the alleged incident. The state prosecutor has therefore halted his probe.

Ms Banon had already said she would attempt to bring a private prosecution if the prosecutor’s office refused to take the case, in which case an independent investigating magistrate will have to reconsider the evidence.

“He will have to be satisfied with being an unconvicted sex attacker, protected by the statute of limitation from criminal charges, but not from legitimate suspicion about his behaviour towards women,” Ms Banon’s lawyer said.

The lawyer, David Koubbi, said the decision “while unsatisfactory, is a first victory for Ms Banon as, after five months of fierce combat, it has been established beyond doubt that her case is not without substance”.

Dr Koubbi argued that the ruling demonstrated that “the facts that she complained of were not ‘imaginary’ contrary to Mr Strauss-Kahn’s claims.”

Another of Mr Strauss-Kahn’s lawyers had an entirely different take on the decision, arguing that her client had been “completely cleared”.