5 alleged Islamic militants were detained in France under suspicion of firing weapons in the woods of eastern France, possibly as training for combat in Iraq.
One suspect was Algerian, while the four others were French - three of Bosnian origin, and another of Algerian origin, judicial officials said. The men ranged from their early 20s to mid 40s. They were arrested Tuesday in two towns in eastern France, Besancon and Pontarlier. Two other men were questioned, then released.
The Paris prosecutor's office has opened an investigation into whether the case has terrorist links. The five were to appear before a judge, who must decide whether to file preliminary charges against them.
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 5 million.
Dozens of youths, some just young teens, are thought to have left from France for Iraq to join the insurgency. Some have been killed there. Police are particularly worried that some French youths with roots in North Africa may be traveling to Iraq without being noticed, traveling via countries like Algeria and Morocco.
French counterterrorism officials worry that such militants could return home with skills learned in combat and a desire to carry out terror attacks in France - even though the country opposed the U.S.-led invasion of Iraq in 2003 and has ruled out sending troops to help U.S. forces battling insurgents there.
Last month, French authorities arrested seven suspects, mostly near the southern city of Toulouse, in an investigation of an alleged al-Qaida-linked network recruiting Islamic fighters for Iraq.
Prosecutors alleged that the recruits were sent first to Egypt to learn Arabic and Islamic teachings "in the most radical schools." Via a cell in Saudi Arabia and linked to al-Qaida, the recruits were then put in touch with a network in Syria that took them to Iraq to allegedly commit terrorist acts, notably suicide attacks.
Police officials said the suspects arrested in eastern France this week had not made definite travel plans for Iraq but were training to fight there.
Judicial officials seemed less certain about the men's intentions. They said they were still looking into why the men were training to fight - though they acknowledged that some of the men spoke of preparing for combat in Iraq.
Police raids of the suspects' homes turned up munitions, handguns and pump and automatic rifles, officials said on condition of anonymity because the investigation was ongoing.
The case was expected to be transferred to Paris anti-terrorism judges on Friday, the officials said.
Prosecutors were expected to file preliminary charges for criminal association with a terror group, which carries a penalty of up to 10 years in prison.