French police have arrested a Parisian taxi driver after explosives were found at his home during a raid over a separate criminal case. They also found a picture of an Islamic State flag on the phone of the man, who was on a watch list of dangerous individuals.

The 23-year-old, whose identity has not yet been revealed, was detained on Sunday at his home in the southeast of Paris, Reuters reports, citing government spokesman Stephane Le Foll.

Police came to the man’s home to question him over his suspected involvement in a burglary case. Police believed the driver had robbed the empty homes of several of his clients after taking them to the airport.

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Officers searched the house on suspicion that some of the stolen goods were hidden there, but instead discovered two sticks of dynamite, as well as several detonators and cables. All of the devices were reportedly fully operational. French media say the explosives were stored dangerously as they were exposed to heat, meaning they could have detonated unintentionally. However, the explosives have now reportedly been destroyed.

In addition to the arsenal, police also found a picture of an Islamic State (IS, formerly ISIS/ISIL) flag on the man's cell phone, Le Foll reported.

Citing sources, Europe 1 TV channel reports that three passports and two driving licenses stolen during a burglary last week were found in the man’s car, possibly intended for use in human trafficking.

Commenting on the findings, Le Foll noted that it is too early to draw conclusions as the investigation is in progress.

“Was [it all] proof an attack was being prepared? The inquiry will tell,” the spokesman is quoted as saying.

The man is said to have already been known to French authorities. He was listed on France’s “Fiche S,” a list of several thousand people who are suspected of posing a security risk due to their radicalization.

The arrest came only three days after a terror attack in Nice in which 31-year-old Tunisian Mohamed Lahouaiej Bouhlel rammed a truck into crowds celebrating Bastille Day, killing some 84 people.

The attack was quickly claimed by Islamic State. Authorities said the attacker had been radicalized only recently and therefore was not on the watch list.

It was the third major terror attack in the country in less than two years.