Tariq Ramadan, an Islamic scholar and Oxford university professor, has been handed preliminary charges in two alleged cases of rape, a judicial source said on Friday.
Ramadan, 55, was arrested and questioned by police in Paris earlier this week over claims by two women, who said he assaulted them in hotel rooms in France in 2009 and 2012. Both women filed their complaints last year.
He has now been charged with connected charges of rape and rape of a vulnerable person, the source said.
He was jailed on Friday, at least temporarily.
Ramadan, who is the grandson of the founder of the Muslim Brotherhood, has strongly denied all the accusations against him. He has also filed a complaint for slander against the writer Henda Ayari, one of his accusers.
Last November, the senior research fellow at Oxford's St Antony's College took a leave of absence from the university after the complaints were filed.
An investigating magistrate in charge of the case followed the request of the Paris prosecutor's office in charging him.
Preliminary charges mean that after a full investigation the suspect can either be freed for lack of grounds or be indicted and sent to trial. The investigation can be lengthy.
The prosecutor's office has asked the judge to keep Ramadan — who holds Swiss nationality — in custody, likely because of concerns he could leave the country.
Women who have testified anonymously during three months of preliminary investigations might now also file rape complaints, sources added.
In the early hours of Friday, Ramadan was taken to the prosecutor's office. It came after a meeting in which one of his alleged victims, a disabled woman named as Christelle, provided information about an intimate part of his anatomy, The Times reported. Ramadan has previously denied having any contact with her.
Ramadan refused to sign the police transcript of his confrontation with Christelle, in which he says he had met her in the hotel lobby in 2009 for 30 minutes.
Christelle has told police that Ramadan has a scar on his groin. Ramadan has confirmed this, according to The Times.
Speaking on French television last year, Christelle told of how she feared for her life when she says Ramadan hit her crutch to make her fall, picked her up by her hair and proceed to sexually assault her over a number of hours.
“It was hell. Blows. Sexual violence. Unspeakable, disgusting language … The more I screamed, the more he hit me,” she said.
She filed a formal complaint against him in October, in which she described her battle with depression and her attempt to commit suicide following the attack.
The other complainant, Ms Ayari, says Ramadan raped her in a Paris hotel room in 2012.
Ms Ayari, 41, who lodged a rape complaint against him on October 20, claimed that for Ramadan, "either you wear a veil or you get raped".
"He choked me so hard that I thought I was going to die," she added.
She said she was encouraged to speak out against him publicly by the "Me Too" campaign.
"It was the #BalanceTonPorc campaign that pushed me to reveal his name," she said, in reference to France's version of the hashtag which means "Expose your pig".
A third woman told Le Parisien in an interview in October that Ramadan sexually harassed her in 2014.
The woman, identified as Yasmina, said Ramadan blackmailed her for sexual favours, threatening to distribute "compromising pictures" of her.
All the complainants said they had initially made contact with Ramadan for spiritual guidance.
In further shocking allegations, Ramadan was accused of seducing four of his teenage pupils in the 1980s and 1990s when he was teaching in his hometown of Geneva.
Four of his former students described the incidents to The Tribune de Genève newspaper, which published their stories at the start of November.
One of them claimed that he tried unsuccessfully to seduce her when she was just 14 years old. He allegedly targeted three others, who were aged between 15 and 18 years old at the time, according to the newspaper's report.
A regular face on French television, the academic is the most prominent figure to be held in France over the sexual assault and harassment claims that have rippled around the world in the wake of the Harvey Weinstein scandal.
Ramadan has called the accusations against him "a campaign of lies launched by my adversaries".