French PM Manuel Valls has warned that France could face chemical or biological attack from terror groups, as MPs debateextending the state of emergency after the Paris attacks.
Belgian police are meanwhile raiding six properties in and around Brussels, linked to suspected Paris attackers Bilal Hadfi and Salah Abdeslam.
It remains unclear whether the suspected organiser of the attacks was killed in Wednesday's raid in Paris.
Friday's attacks killed 129 people.
Mr Valls was addressing the French parliament ahead of a vote to extend the state of emergency by three months.
He told MPs that "terrorism hit France, not because of what it is doing in Iraq and Syria ... but for what it is".
"What is new are the ways of operating; the ways of attacking and killing are evolving all the time," the prime minister said.
"The macabre imagination of those giving the orders is unlimited. Assault rifles, beheadings, suicide bombers, knives or all of these at once."