The four were picked up Friday night in the Paris region, according to the police sources said, speaking on customary condition they not be named.
French media suggested the action might be linked to Saturday night's soccer match between France and Algeria the first since the North African nation won independence from France in 1962.
The newspaper Le Monde reported Saturday that among the four detained was Nasreddine Mamache, currently on trial along with 23 others for allegedly belonging to a support network for the Armed Islamic Group, radical Algerian insurgents.
Mamache was detained after investigators overheard references to "taking action" on Saturday, Le Monde said.
During a search of the suspects' homes, police found bomb-building manuals, false papers and a statement claiming responsibility for actions in Algeria from a group called the Guardians of Salafist Preaching, Le Monde said.
The police sources would not solidly link the detentions to the match. Nor would they say whether there the detentions were linked to earlier arrests in connection with a plot by Islamic extremists to attack U.S. interests in France. Nine people have been jailed in France in connection with the plot
The suspects had been questioned in 1994 when police began dismantling a support network for the Armed Islamic Group, or GIA, the police sources said.
The dismantling of the so-called Chalabi network, named for its leader Mohamed Chalabi, culminated in a November 1998 trial of 138 defendants in a prison gym outside Paris.
Nearly 100 defendants were convicted of taking part in the network, which sent arms to the GIA, radical Muslim insurgents, and provided false identity documents, lodging in France and other support for insurgents.
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