Oxford professor Tariq Ramadan is to remain in custody pending a possible trial for allegations of rape, a source from the prosecutor's office said.
The decision was made by a French judge on Tuesday to keep him behind bars after a debate between Mr Ramadan's lawyers, prosecutors and magistrates.
The prominent Islamic scholar, who denies the allegations, was notified on Friday that he would be the target of a full investigation and had been in detention ever since. The inquiry will now be taken a step further, after the judge decided not to release him.
Under French law, investigating magistrates can still decide not to hold a trial, depending on the evidence. Temporary custody is usually reserved for cases where the accused might be a flight risk. Mr Ramadan - who holds Swiss nationality - is likely being held in custody because of concerns he could leave the country.
Mr Ramadan, 55, was arrested and questioned by police in Paris last 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.
On Friday, he charged with connected charges of rape and rape of a vulnerable person, and was jailed, at least temporarily.
Mr 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.
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.
Mr Ramadan has called the accusations against him "a campaign of lies launched by my adversaries".
Over 27,000 people have signed a petition pledging their support for Mr Ramadan. The petition contains an open letter which says the accusations are "invested in a smear campaign which is the continuation of the demonisation efforts that have been aimed at him since the beginning of his intellectual and militant commitment in 1990".
