France's intelligence chief believes that Islamist extremists like those who carried out two waves of attacks in Paris last year will look to increase their capacity to kill by using booby-trapped cars and bombs.

The remarks by Patrick Calvar, testifying before a parliamentary commission examining French means to fight terrorism, were published on Tuesday in a 300-page report.

The Nov. 13 attack on a stadium, a concert hall, bars and restaurants were carried out by suicide bombers and assailants with assault rifles. But Calvar said in his May 24 testimony that he thinks attack methods will evolve.

He said: "I'm convinced they'll go to booby-trapped vehicles and bombs, thus upping their power."

The commission's work uncovered intelligence letdowns that led to the failure to foil the attacks that killed 147.