French authorities have for the first time confiscated the passports of six nationals who were allegedly planning to travel to Syria to join jihadists.
Interior Minister Bernard Cazeneuve said the intelligence services believed the men wanted to join the Islamic State (IS) militant group.
The measure is part of new counter-terrorism laws adopted last November.
Meanwhile, France has deployed an aircraft carrier off Bahrain to be used against Islamic State (IS) militants.
Planes from the Charles de Gaulle carrier will be used against IS positions in Iraq, a spokesman for Defence Minister Jean-Yves Le Drian said.
The first Rafale fighter jet took off on Monday morning from the carrier as it sailed about 200km (120 miles) off the northern coast of Bahrain.
Correspondents say that the deployment of the warship will halve the time it takes for military aircraft – which normally fly from the United Arab Emirates – to reach Iraq.
France began Operation Chammal in support of the US-led coalition against IS in September.
Mr Cazeneuve said authorities had acted against the six men after their departure to Syria appeared to be imminent.
Their passports and identity cards have been confiscated for six months, after which the order can be renewed. They have the right to appeal against the move in court.
Reports in French media said some of the men were reported to the authorities by relatives using a newly established telephone hotline, while others were identified by police investigations.
French officials quoted by the Reuters news agency estimate that about 400 French citizens are in Syria, 180 have returned to France, 200 want to go and 200 are somewhere in Europe trying to get there.
France has been on alert after 17 people were killed in attacks on the satirical Charlie Hebdo magazine and a Jewish supermarket in January.
UK officials think some 600 Britons have fought in Syria, with 300 having returned. Police can now seize the passports of nationals trying to leave the country for up to 30 days, in addition to temporarily stopping citizens suspected of involvement with IS from entering Britain.
Last week, three British schoolgirls were said to have left London to travel to Syria through Turkey.
About 550 German citizens have also fought in Syria and about 180 are believed to have returned, according to German officials. Under a draft law, it too plans to confiscate identity cards of suspected jihadists for up to three years.
bbc news – culled from http://www.bbc.com/news/world-europe-31587651