The operation "is not linked only to Toulouse, it's on all of French territory, is linked with a form of radical Islam and is in full accordance with the law", Sarkozy said.

He said Friday's operation was only the start.

"We have some extremely precise questions to ask a certain number of people and what happened this morning will continue," said Sarkozy, in the thick of a heated campaign for France's two-round April-May presidential election.

"There will be other operations that will continue and will also allow us to expel from our national territory a certain number of people," he added.

Sarkozy also defended France's decision this week to bar some Muslim preachers from entering the country, saying: "We don't want people who advocate values contrary to the republic to be invited to our territory."

Police sources said the raids were "not directly linked" to the Toulouse shootings but targeted at extremists networks.

Police said Kalashnikov assault rifles and other weapons were seized during the raids.

Among those arrested was Mohammed Achamlane, the head of a suspected extremist group called Forsane Alizza, the sources said, with three Kalashnikovs, a Glock pistol and a grenade were seized from his home.

The arrests came a day after Merah, who was shot dead by a police sniper on March 22 at the end of a 32-hour siege at his flat in Toulouse, was buried in the city under heavy police watch.