France will maintain its national security alert system Vigipirate at the highest level, which means definite threats, in greater Paris area in northern France, a French security official said on Saturday.

"We are exposed to threats. So it's important that the Vigipirate, lifted Wednesday in Ile-de-France, is strengthened in the coming weeks," French Interior Minister Bernard Cazeneuve told reporters Saturday morning after an inter-ministerial emergency meeting held in Elysee.

"We maintain all the measures taken by the Prime Minister and we will strengthen them to protect different places, such as places of worships," said Cazeneuve.

Since Wednesday due to the attack on the headquarters of French satirical magazine Charlie Hebdo and Montrouge shooting, France has raised Vigipirate security alert to Scarlet, its highest level, in greater Paris area and the region of Picardie, where security was reinforced at public places, including major stores, religious centers and public transport.

French President Francois Hollande said on Friday that high vigilance is still necessary as danger to the country is not over yet, despite the death of three shooters who committed the deadliest attacks in the country in 50 years.

Cherif Kouachi and Said Kouachi, perpetrators of Wednesday's Charlie Hebdo terrorist attack, were killed Friday afternoon around 16:55 local time (1555 GMT) in an assault by a French security force.

Meanwhile, French security forces launched another operation at the Porte de Vincennes neighborhood of Paris and neutralized Amedy Coulibaly, who shot dead a policewoman at Montrouge on the southern edge of Paris on Thursday and took several hostages in a Jewish supermarket at about 13:55 local time (1255 GMT).