Strauss-Kahn expected to be told he can leave US for first time since arrest on charges he sexually assaulted hotel worker

US prosecutors have confirmed they have asked a judge to dismiss all charges against Dominique Strauss-Kahn, the former French presidential hopeful accused of attempting to rape a hotel maid.

The move brings to a controversial end one of the biggest sex scandals in decades. Strauss-Kahn is expected in court on Tuesday, where he will be told he is a free man and will be allowed to leave the country for the first time since his arrest in May on charges that he attempted to rape hotel worker Nafissatou Diallo.

In court papers filed on Monday, Manhattan district attorney Cyrus Vance said: "The nature and number of the complainant's falsehoods leave us unable to credit her version of events beyond a reasonable doubt, whatever the truth may be about the encounter between the complainant and the defendant.

"If we do not believe her beyond a reasonable doubt, we cannot ask a jury to do so."

Diallo's lawyer, Ken Thompson, attacked the decision: "The Manhattan district attorney, Cyrus Vance, has denied the right of a woman to get justice in a rape case," he said. "He has not only turned his back on this victim but he has also turned his back on the forensic, medical and other physical evidence in this case. If the Manhattan district attorney, who is elected to protect our mothers, our daughters, our sisters, our wives and our loved ones, is not going to stand up for them when they're raped or sexually assaulted, who will?"

Diallo and her lawyers met the district attorney's team on Monday afternoon. Thompson said the meeting lasted 30 seconds and that prosecutors told Diallo the case was being dismissed because she had repeatedly lied to them. He called the meeting "disrespectful".

Protesters held a demonstration in support of Diallo outside Vance's office and demanded that he step down.

Earlier in the day Thompson had made a last-ditch effort to save the prosecution by having the district attorney removed from the case before he could request its dismissal.

Vance's office initially gave unqualified backing to Diallo, calling her statement "a compelling and unwavering story".

Her story appeared to be backed by forensic evidence; his semen was found on her uniform and the carpet of the room where the incident took place. While Strauss-Kahn's lawyers have never denied a sexual encounter took place, Diallo's credibility came under fire as it emerged she had lied to officials on numerous occasions, including to immigration officials about claims that she had been gang raped in Guinea, her home country.

As credibility issues surfaced, Diallo's lawyers clashed with Vance's office and fought their case in public. Diallo filed a civil lawsuit against the former IMF boss on 8 August, a move that legal experts said made Vance's position even more difficult.

Pierre Hourcade, a French attorney who is also admitted to practice law in New York, said: "Dismissal does not mean he is innocent, simply that the district attorney doesn't believe the case can go to trial."

He said some people in France were surprised that the US authorities prosecuted the case so vigorously initially, only to cool on the case equally as fast. "It's not that he doesn't believe her, it's that he doesn't believe her to be a good victim. That's the way that the American system is built," he said.

Defence lawyer Ron Kuby said Vance mishandled the case from the start: "This case could be used as a text book for what not to do," he said. Kuby said Vance had been too quick to bring charges, had made statements that were "far in advance of the evidence" and "rushed ahead to indict him when they didn't have to".

Stuart Slotnick, a white collar crime expert at Buchanan Ingersoll & Rooney and a former Federal prosecutor, defended Vance. "This is the same DA's office that prosecutes people who rape prostitutes. Those are very difficult cases to bring," he said.

He said it was clear that she had lied to the prosecutors on numerous occasions and that they no longer felt they could trust her.

"These are the people with the greatest access to evidence, to the complainant, and they don't believe in the case," he said. "A prosecutor should not prosecute a case that they don't believe in."