France's top security official says militants from the Islamic State group have threatened to kill civilians in the coalition of countries arrayed against the extremists.

Interior Minister Bernard Cazeneuve says he is confident in the country's security.

Cazeneuve said Monday "this threat to kill civilians, added to the execution of hostages and to the massacres, is yet another demonstration of the barbarism of these terrorists, justifying our fight without truce or pause."

He added that "France is not afraid because it is prepared to respond to their threats."

The al Qaeda breakaway group, which wants to establish an Islamic state, or caliphate, rules by its harsh version of Islamic law in territory it captured straddling the Syria-Iraq border. France and the U.S. have conducted airstrikes in Iraq against the militants.