A man shot dead at Paris's Orly airport after attacking a soldier was under the influence of drugs and alcohol, the results of an autopsy showed.

Ziyed Ben Belgacem was shot dead on Saturday as he tried to seize the weapon of a female soldier at the airport while shouting, "I am here to die for Allah."

The 39-year-old had a blood alcohol level of 0.93 grams per litre, almost twice the legal driving limit in France, and had also taken cannabis and cocaine, the AFP news agency reported, citing judicial sources.

Investigators are still trying to determine what motivated Saturday's assault by Belgacem, which led to a major security scare and the temporary closure of the capital's second busiest airport.

Early investigations indicated that Belgacem, who had an extensive criminal record including convictions for drug dealing and armed robbery, had been influenced to carry out the attack while in prison.

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Ben Belgacem's father insisted his son was not a "terrorist".

"My son was not a terrorist. He never prayed, and he drank," the father, who was in shock and whose first name was not given, told Europe 1 radio.

Before the attack at the airport, Belgacem had opened fire on a police officer at a checkpoint in the northern Paris suburb of Garges-les-Gonesse and had later stolen a car.

The attack at Orly comes with France still on high alert after a wave of attacks that have claimed more than 230 lives in two years.

Following the coordinated attacks around Paris in November 2015, the French government declared a state of emergency that was extended in December for the fifth time and will remain in force until July 2017.

The violence has made security a key issue in France's two-round presidential election on April 23 and May 7.