Forensic experts enter a building as they work on the scene in Saint-Denis, near Paris, France, November 19, 2015 the day after a police raid to catch fugitives from Friday night's deadly attacks in the French capital.[Photo/Agencies]

PARIS - France could face the risk of chemical or bacterial warfare in its fight against Islamist militants, French Prime Minister Manuel Valls said on Thursday.

"We must not rule anything out. I say it with all the precautions needed. But we know and bear in mind that there is also a risk of chemical or bacteriological weapons," Valls told parliament.

"The macabre imagination of the masterminds is limitless," he said in a speech in the lower house of parliament meant to gain approval to an extension of the state of emergency.