PARIS, July 14 (Reuters) - Criminal intent is suspected in two fires at a LyondellBasell industries facility near Marseilles airport on Tuesday, a source close to the French government said.
"The simultaneous explosion of the tanks, which are spaced about 500 metres (yards) from each other, is not the result of a technical accident", the source said.
"The thesis of criminal intent is clearly being considered," the source added.
Firemen were still trying to extinguish one of the fires which triggered a vast smoke plume in the sky of France's second largest city, a Reuters witness reported.
Earlier, the Bouches-du-Rhône department said in a statement the smoke did not pose immediate health risks. Air traffic at Marseilles Provence airport was unaffected, it said. (Reporting by Yann Le Guernigou; Writing by Matthias Blamont)