PARIS, Jan. 12 (Xinhua) -- French President Francois Hollande announced Saturday to reinforce the country's anti-terror alert to the highest level following Paris' military commitment to help Malian authorities stop Islamist rebels' offensive.
"The fight against terrorism requires to take all precautions measure here in France. I asked ... to reinforce the vigipirate plan to conduct for monitoring our public buildings and our transport infrastructure," Hollande said after heading a special meeting of the defence council.
"The military operation in Mali confirms France's determination not to give in to terrorist blackmail," the president added.
As French forces carried out air strikes for the second day on Saturday against Islamist rebels in Mali, the Jihadists warned that France's military intervention against them in northern Mali will put "not only for French hostages, but also for all French citizens wherever they find themselves in the Muslim world" at risk.
Ealier in the day, Defense Minister Jean-Yves Le Drian believed that Denis Allex, a secret agent abducted in Somalia since 2009, was killed by his captors in a rescue raid.
"Last night, the commando of the DGSE ... faced strong resistance. Fights of great violence took place during which, evidence suggests that Denis Allex was killed by his captors," he told reporters.
He also added that a French soldier was missed during the operation.
The Vigipirate plan, implemented in Match 2003, has four levels: yellow, orange, red and scarlet, from the lowest to the highest.
A major terrorist bomb explosion hit the Paris subway in 1995. It killed eight people and wounded 200 others.