French police arrested 19 people on Friday in a crackdown on suspected Islamist networks after an Al-Qaeda-inspired gunman killed seven in southern France this month.

"There will be further operations, allowing us to expel a number of people who have no business in the country," said French President Nicolas Sarkozy.

The operation came a week after the 24-year-old Muslim gunman Mohamed Merah claimed responsibility for killing three national paratroops from ethnic minorities and four Jewish in the southern cities of Toulouse and Montauban.

Friday's raids were not directly related to Toulouse's killing spree but it's in connection with a form of Islamist radicalism, Sarkozy added in an interview on Europe 1.

People suspected of conducting radical Islamist activities had been arrested in swoops in Toulouse, Nantes in western France, the Paris region and southeastern France.

A number of weapons, including Kalashnikov rifles, were seized in Friday's operation, the president said.

Merah, of Algerian origin, was killed last Thursday when he tried to shoot his way out of his apartment following a 32-hour police siege in Toulouse.

On Thursday, France prevented four Muslim imams from entering its territory to participate in an Islamic conference next month as they "represent a high risk of disturbing the public order."