Fresh problems for Dominique Strauss-Kahn

The case throws up a fresh headache for the Frenchman just as his legal team felt he was "winning the tide" after the near collapse of sex assault charges in New York that brought his career at the International Monetary Fund to an end. Strauss-Kahn - who was considered a leading contender for the French presidency until the scandal - is expected to counter-claim against Banon, a routine procedure in France. His lawyers declined to comment yesterday.

Ms Banon, 32, filed her complaint earlier this week over an incident she alleges occurred in 2003 when she went to interview the former French finance minister in an otherwise empty Paris apartment.

Her lawyer, David Koubbi, said there was "physical" evidence to back her case, although he declined to say if that included text messages or recordings.

Strauss-Kahn, 62, was the favourite to unseat conservative president Nicolas Sarkozy by running for the Socialist Party in next year's election until his arrest in May threw his political future into question.

That case appeared to weaken last week when US prosecutors said they had doubts about the credibility of the hotel chambermaid who has alleged Strauss-Kahn tried to rape her when she went to clean his room, leading a public feud with her lawyers.

A court released Strauss-Kahn from house arrest and signs that the case may be unravelling raised the prospect that he could return to France in the months ahead and take a role supporting the left's election campaign.

However, a person close to the case said prosecutors want at least two or three more weeks to investigate.

The source also said that no plea deal was sought in a meeting this week with Strauss-Kahn's lawyers.

Ms Banon is a journalist and author of three books, including a novel that gives a fictionalised account of the alleged incident with Strauss-Kahn.

And in 2007 she gave a graphic account of the alleged assault in a television talk show - with his name bleeped out - but had never taken legal action until this week.

For Ms Banon's case to stand up, it would need evidence of attempted rape rather than just sexual assault, since in France attempted rape charges can be brought up ten years after the event but assault charges expire after three years.

Attempted rape carries a penalty of up to 15 years in France.

While Strauss-Kahn's allies have rallied round him, French voters no longer see him as presidential material, with an opinion poll this week finding two-thirds did not want him to be a candidate in the 2012 election .

Meanwhile, his successor at the IMF, Christine Lagarde, won a legal reprieve yesterday when a French court delayed a decision on investigating her role in a €285 million arbitration deal.

In 2008 Ms Lagarde was France's finance minister when business magnate Bernard Tapie won what some saw as a suspiciously generous settlement with a French state-owned bank over the mishandled sale of sportswear maker Adidas in the 1990s.

A prosecutor wants an investigation into Ms Lagarde's role in the deal, saying he suspects she abused her authority. Critics have said she should have appealed the arbitration decision.

A commission at the Court of Justice of the Republic convened yesterday to decide whether to launch an investigation. After deliberating, it said it would delay its decision until 4 August because one of the judges on the panel said he didn't want to be involved in the case.

Gerard Palisse, who presides over the panel, said: "One of the members of the panel let us know, belatedly, that he was obliged to recuse himself."

No reasons were given for the move.