The police and judicial officials say the five had allegedly trained for combat in hopes of joining the Iraqi insurgency. Seven other men went on trial in Paris on Wednesday, suspected of involvement in an al-Qaida-linked recruitment network, also aimed at Iraq.
A threatening new message from Al-Qaida leader Osama bin Laden has raised concerns that the organization is plotting attacks in Europe.
The message, released Wednesday, accuses Pope Benedict of helping in a "new Crusade" against Islam.
It also warns of a "severe" reaction to European publication of cartoons seen by Muslims as insulting Islam's Prophet Muhammad.
In the latest French arrests, seven people were taken into custody Tuesday in the southern cities of Toulouse, Montpellier and Carcassonne, police and judicial officials said on condition of anonymity.
Two of those picked up were released Wednesday; the others were still being held.
In a search of suspects' homes, police found knives, camouflage gear and Islamist documents, authorities said.
Authorities believe they had been in contact with radical Islamists who allegedly trained to fight in Iraq by firing weapons in the woods of eastern France. Those suspects were rounded up in a November sweep.
Preliminary charges were filed against five of the November suspects for "criminal conspiracy with a terrorist organization," a broad charge often used in terror-related cases in France. Officials said the group had not made definite travel plans for Iraq, but was training to fight there.
Police and anti-terror investigators say anger over the Iraq war has radicalized some young Muslims in France, which has Western Europe's largest Muslim population, estimated at five million.
Judicial authorities believe dozens of youths, some just young teens, have left from France for Iraq to join the insurgency. Some have been killed there. Police have been worried that some French youths with roots in North Africa may be travelling to Iraq, without being noticed, via Algeria and Morocco.
The seven men on trial in Paris are suspected involvement in an al-Qaida-linked network that recruited young French men on the streets of eastern Paris and sent them to fight in Iraq's insurgency.
The men are charged with "criminal conspiracy with a terrorist organization." The network was dismantled in 2005. Judicial officials believe about 10 people were sent to Iraq - at least three of whom died there - via the Paris network.
French counterterrorism officials are concerned that such militants could return home with skills learned in combat and carry out terror attacks in France, even though the country opposed the U.S.-led invasion of Iraq in 2003.
Source: The Canadian Press (English)
See also: Paris: al-Qaeda Iraq recruiting network trial