French writer Tristane Banon claims the IMF chief acted like a 'rutting chimpanzee' in an attack on her nine years ago

A French writer who claims Dominique Strauss-Kahn sexually assaulted her nine years ago is to file an official complaint, her lawyer has announced.

Tristane Banon previously described the attack, which happened when she was in her early 20s, in a television programme in 2007, when she called Strauss-Kahn, whose name was bleeped out, a "rutting chimpanzee."

She says she consulted a lawyer at the time, but was persuaded not to take action by her mother, a regional councillor in the Socialist party and friend of the Strauss-Kahn family. Banon is goddaughter to Strauss-Kahn's second wife.

Banon's lawyer, David Koubbi, said: "We are planning to make a complaint. I am working with her."

Strauss-Kahn was remanded in custody today after appearing in a New York court accused of a sexual attack on a hotel maid.

The 62-year-old head of the International Monetary Fund – who was widely tipped to be France's next president – was refused bail by the judge, Melissa Jackson, who ruled he might attempt to flee the US. His offer to post bail of one million dollars was turned down.

DSK, as he is known in France, will now stay in prison until his next court hearing on May 20. He faces charges of attempted rape, sex abuse, a criminal sex act, unlawful imprisonment and forcible touching and could face up to 25 years in prison.

Strauss-Kahn denies the charges.

Koubbi said Banon, now 31, was "literally blown over" when she heard the claims Strauss-Kahn had attacked a hotel chambermaid in New York. "At the same time, she was certainly not surprised," he said.

Across France, after the shock of Strauss-Kahn's arrest, came speculation, self-pity and conspiracy theories.

For some, the story of Strauss-Kahn's fall from presidential hopeful to prison cell was a combination of sordid tale and Shakespearean tragedy. For others the story was so extraordinary it smacked of a set-up.

Only three weeks ago, Strauss-Kahn evoked such a possibility in an interview with French newspaper Libération when he said he thought he was under surveillance and named the three principal difficulties he foresaw if he was to stand for the presidential elections.

"Money, women and the fact I am Jewish." He added: "Yes, I like women ... so what?" He said he could see himself becoming the victim of a honey trap: "a woman raped in a car park and who's been promised 500,000 or a million euros to invent such a story ..."

But not in his or his Socialist party's worst nightmares, nor in President Nicolas Sarkozy's wildest dreams, could anyone imagine Strauss-Kahn, nicknamed with almost tacit admiration the 'Great Seducer', being at the epicentre of what was described as a "political earthquake".

Jean-Marie Le Guen, a Socialist party MP who has known Strauss-Kahn for 25 years, said the story was "not credible" and inconsistent with what he knew of the politician's character. "Seduction, yes, but no way would he use constraint or violence. A certain number of facts, and certain aspects of the story we are hearing from the press, make this not credible."

He said Strauss-Kahn had not fled the scene of the alleged crime as reported but had lunched in New York before catching a flight booked weeks previously.

France-Soir reported that when plain-clothed police officers approached the politician in the first-class section of the Air France plane bound for Paris, he looked up at them and asked: "What's the matter?"

Le Guen said his friend knew he would be the target of mud-slinging but added: "What they are asking us to believe … it's just hallucinations. I'm a doctor and I know this can happen. We knew there would be hyper-violent attacks on him [Strauss-Kahn]. We could hear the knives being sharpened in preparation."

Libération editor Nicolas Demorand suggested France was having its first sex scandal "à l'anglo saxonne" and was "brutally entering a zone of public debate which, up to now whether because of the cultural exception, the 'latin' identity or democratic weakness has been confined to rumours and gossip among a small inner circle".

"Politicians … enjoy a particular tolerance on this subject," he wrote. "Part of the shock comes also from the unusual scene, until now unthinkable here: police arresting a top-level politician on a matter of morals."

There is sympathy for Strauss-Kahn's third wife, television journalist Anne Sinclair, who Le Guen said was bearing up with "strength and courage".

In a spasm of self-flagellation, political commentators spoke of the affair as a disgrace and humiliation for France, referring to the country as "the victim" in the affair. Nathalie Kosciusko-Morizet, the ecology minister, did at least mention the 32-year-old chambermaid allegedly attacked by Strauss-Kahn. "As well as the presumed victim, the chambermaid, there is a proven victim … France. We should remember the facts are very serious; in France we tend to treat things like this a little bit lightly," she told news agency AFP.

Of the pictures of Strauss-Kahn being led in handcuffs by New York police, criticised by some, including Le Guen as "hyper violent", Kosciusko-Morizet said the French politician was a suspect like any other. "I have confidence in American justice … it's so French to see conspiracies everywhere, it's something I believe that's in our culture."

The Socialist party was holding an emergency meeting to decide on how to react to the crisis in its ranks. Two months from the closing date for the party's primary election in October, Strauss-Kahn was the opposition's main hope of unseating Sarkozy.