French anti-terrorism police were interrogating a man employed as a baggage handler at Paris's Charles de Gaulle Airport, trying to determine why he allegedly had a cache of weapons and explosives in his car in an airport parking lot and whether he had links to Osama bin Laden's al Qaeda terror network.

His arrest was the latest in a string of detentions of suspected Islamic militants in France at a time when officials are warning that al Qaeda cells in Europe may be planning a new and spectacular terrorist attack.

Abderazak Besseghir, a 27-year-old Frenchman of Algerian origin, was arrested Saturday after a tip from a passenger who said he saw the man acting suspiciously at the trunk of his car. Police followed Besseghir throughout the day and arrested him when he returned to his car, and inside they found a pistol, five cakes of plastic explosives, two detonators and a fuse, according to police and French media outlets.

French television showed Besseghir being moved to the headquarters of the criminal investigations division in a blue van and under heavy guard, including police in bulletproof vests running beside the vehicle.

Later, anti-terrorism police went to Besseghir's home in the Bondy suburb of Paris, and took his father, two brothers and another man, described as a family friend, into custody, according to the French television channel LCI. Under French law, terrorism suspects can be held for up to four days before being placed under formal investigation, one step short of being charged, or released.

Initial police and news reports said Besseghir had no criminal record and no known links to Islamic radical groups, and one news agency reported that someone else may have put the weapons and explosives in his car. The case has raised concerns among security officials here because Besseghir, as a baggage handler, had a badge giving him access to the most restricted parts of the airport, including the runway and freight areas.

Security at Charles de Gaulle has been tightened since last year, when British citizen Richard C. Reid boarded a Paris-to-Miami flight at the airport with explosives hidden in his shoes. He was overpowered by passengers and crew members in midair as he tried to light the bombs.

European governments have been reluctant to follow the U.S. example of issuing threat warnings. But following a series of discoveries over the last several weeks in Europe, particularly in France, officials have issued warnings that a new attack may be in the works.

On Dec. 16, police raided an apartment in a northern suburb of Paris and found chemical protection suits, stacks of cash, empty chemical containers and suspicious liquids, leading the Interior Ministry to announce that it had thwarted a potential chemical attack in the city. Several Algerians and a Moroccan were arrested.

On Dec. 20, anti-terrorism police announced they had disrupted a militant cell with links to separatist guerrillas in Chechnya. The cell was plotting attacks against Russian interests here, police said, possibly including the large and heavily fortified Russian Embassy.

The Caucasus region, where Chechnya is located, "is the next place where the threat will be concentrated," said a senior Western counterterrorism official, "and the role of the non-Chechens is increasing."