The country's interior minister Bernard Cazeneuve moved on Wednesday to reinforce protection at industrial sites across France amid fears more locations could be vulnerable.
The move comes after a twin explosion at a petrochemical plant in in Berre-l'Etang near Marseille-Marignane airport, that authorities believed was purposeful and "malicious" act.
Cazeneuve sent out an urgent note on Wednesday to all local authorities asking them to make contact with those responsible for the industrial sites so inspections can be carried out on all sites and security systems could be checked.
Special focus was placed on the 1,171 highly sensitive sites classed as SEVESO – meaning that if there was an accident it could spark serious and immediate consequences.
The explosions at Berre-l'Etang saw two tanks full of petrol and naphtha -- a flammable liquid distilled from petroleum -- caught fire after the blasts and a thick cloud of smoke was visible several kilometres away.
The fire in the first tank of petrol was extinguished fairly quickly, but firefighters only managed to put out the second blaze by late morning using foam, local authorities said.
The plant is operated by chemical firm LyondellBasell, which said the fires were not toxic.
A source close to the case said investigators believed the explosions were the result of "a malicious act."
"The probability that these two fires in tanks 500 metres (1,640 feet) apart could be accidental is very low. Investigators are leaning towards the theory of a voluntary act," another informed source said.
Prosecutors have opened a probe into the incident.
Asked whether there was any link with the theft earlier this month of explosives and detonators from a military base some 30 kilometres (19 miles) away, local official Jean-Marc Senateur said it was too early to tell.
Thieves broke into a vast army logistics base in Miramas overnight on July 5, stealing at least 150 detonators and a stock of plastic explosives.
The facility, which houses some 200 soldiers, is used to stockpile weapons for foreign missions, such as those in Africa.
The thieves have still not been caught.