France's intelligence chief believes Islamist extremists like those who carried out two waves of attacks in Paris last year will look to use booby-trapped cars in the future.
The remarks by Patrick Calvar, testifying before a parliamentary commission examining French efforts to fight terrorism, have been published in a 300-page report.
Last year's November 13 attack on a stadium, a concert hall, bars and restaurants were carried out by suicide bombers and assailants with assault rifles.
But Mr 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 issues which led to authorities' failure to foil the attacks that killed 147 people.
Mr Calvar said: "We know very well they're going to use this mode of operating.
"They're going to end up sending commandos whose mission is to organise terrorist campaigns without necessarily going to the assault with death awaiting them."
He also raised the possibility of extremists using "dirty bombs" and the natural poison ricin, saying several groups had studied the toxin in the past.
The Armed Islamic Group, which caused terror in Algeria in the early 1990s, was looking to put the substance on car door handles to create a panic effect, Mr Calvar said, and this tactic was also studied in northern Iraq and in the remote Pankisi Valley in Georgia, once a stronghold of Chechen militants.
Mr Calvar did not elaborate on when this new approach to attacks could become an imminent threat to France or other western targets. He noted before the commission that he cannot reveal all that he knows.
Several associations representing victims and their families also met French interior minister Bernard Cazeneuve.
Mr Cazeneuve had earlier rejected one of the 40 proposals contained in the report - the establishment of an American-style intelligence agency that combines numerous others currently existing in France.