The Frenchman shot dead by troops patrolling at Paris' Orly airport after trying to take one of their weapons told them he was "here to die for Allah", a prosecutor said Saturday.

"Put your weapons down, I'm here to die for Allah. In any case people are going to die," Ziyed Ben Belgacem told the troops, according to Paris prosecutor Francois Molins.

Along with his father and brother, a cousin of the attacker has now been detained, Molins told a press conference.