French police have found bomb-making materials and arms after investigating suspected radical Islamists arrested in a "vast anti-terrorist operation" over the weekend, Paris prosecutor Francois Molins said on Wednesday.

Molins added French anti-terrorism unit found in a garage in a Parisian suburb used by one of the suspects, a shotgun, a revolver, bags of potassium nitrate, sulphur and a pressure cooker.

Adding to that, a list name of Jewish groups in the Paris region was found at his home.

"These are all products used to make what we call improvised explosives," he noted.

Last Saturday, French police launched a nation anti-terror raid to dismantle a radical Islamists cell during which one suspect of a grenade attack on a kosher grocery was killed and 12 others were arrested.

"We are clearly confronted with an extremely dangerous terror network," Molins said adding that "it's essential to extend (suspects) stay in custody."

"It is therefore necessary when everything is implemented, using all the powers vested in me by law, to terminate its actions and prevent any risk of a terrorist attack," he stressed.