A fresh attempted rape suit against former IMF boss Dominique Strauss-Kahn threatened Tuesday to wreck his hopes of returning to frontline French politics if acquitted at his New York trial.

Tristane Banon, 32, planned to lodge "a complaint for attempted rape" around eight years ago against Strauss-Kahn with French prosecutors Tuesday, her lawyer David Koubbi told the news magazine L'Express on its website.

The French writer and journalist had already publicly accused Strauss-Kahn of trying to force himself on her "like a rutting chimpanzee" but said she was persuaded at the time that no one would take her word against the powerful politician's if she sued.

Strauss-Kahn was charged in New York in May with trying to rape a hotel maid but a judge freed him from house arrest last week after prosecutors said they had doubts about that accuser's credibility.

The US case continues, but an acquittal now looks increasingly likely.

Banon told L'Express that "seeing Strauss-Kahn freed then afterwards dining in a fancy restaurant with friends, that makes me sick."

"I can't bear hearing that I am liar because I hadn't lodged a complaint" immediately, Banon told L'Express, saying Strauss-Kahn had "his hands in my pants after he ripped off my jeans and bra."

She added: "Eight years ago when I talked about bringing a complaint, everyone had me believe that it would lead nowhere. In these matters it is one person's word against another."

The revelations that the New York maid is suspected of lying to police has raised expectations that Strauss-Kahn will be cleared in that case.

Some of his allies in the French opposition Socialist Party have suggested he could return to fight Nicolas Sarkozy in next year's presidential election.

Before the New York scandal he polled as the person most likely to beat Sarkozy. Some of Strauss-Kahn's alleged the arrest was the result of a set-up.

Banon's legal action complicated the prospects of him returning in glory and prompted awkward questions for members of the Socialists, whom Banon says knew about her alleged ordeal at the time.

She said former Socialist Party chief Francois Hollande, currently polling as the leading Socialist presidential candidate, was aware of the accusations.

On Monday, Hollande declared he had "no detailed knowledge" of the alleged incident, which Koubbi said took place in 2003.

A survey by pollster BVA carried out before Banon's announcement and published on Tuesday said 54 percent did not want Strauss-Kahn to return to the election race even if cleared in New York.

Nevertheless, 42 percent of those polled in a separate survey judged he would make a good president.

In France, attempted rape is punishable by 15 years in prison.

Strauss-Kahn's lawyers Henri Leclerc and Frederique Baulieu hit back by threatening Banon with a defamation suit, dismissing her claims as "imaginary".

Banon first publicly talked of the encounter in a television broadcast in 2007, saying she had to beat off the politician as he pawed at her like "a rutting chimpanzee."

Banon's mother, Socialist politician and blogger Anne Mansouret, confirmed she had advised her daughter at the time not to make a formal complaint for fear of hurting her career in journalism.

"Perhaps I underestimated the trauma that could have caused to a very young woman," Mansouret told RTL radio Tuesday, saying she respected Strauss-Kahn's "intellectual capacities" but thought he should "get treatment".

"I always thought there was something very worrying about his behaviour, as someone who has enormous responsibilities... and was setting his sights on even bigger ones."