Four French terror suspects repatriated from the US prison in Guantanamo Bay must remain in detention while further investigations are carried out.
The four spent more than two years at Guantanamo Bay
A court in Paris rejected their request for conditional release.
Mourad Benchellali, Nizar Sassi, Imad Achab Kanouni and Brahim Yadel, all of north African origin, were detained by American forces in Afghanistan in 2001.
They returned to France last week after being held for more than two years at the US naval facility in Cuba.
The four men are being questioned about their links to what investigators describe as terrorist organisations and the possible use of forged documents.
Further requests for their release will be considered by 20 August.
Interior Minister Dominique de Villepin has said a thorough investigation into the background of the four is necessary.
"It is very important to ask all the questions that the French people are asking themselves: What links with terrorist groups? What participation in, or association with this or that attack?" he told RTL radio on Wednesday.
"I think it's important to do everything to find the truth."
William Bourdon, one of the lawyers for Mr Benchellali and Mr Sassi, said that keeping the men in detention would be inhumane as the evidence against them is "questionable".
Defence lawyers also say their clients were mistreated during their time at Guantanamo Bay, where about 590 non-US terror suspects are still being held.
The French foreign ministry says discussions are continuing with the US authorities to try to secure the release of three other French Guantanamo inmates.