"Shipments at Fos are blocked," an Exxon France spokeswoman said.

Exxon Mobil's 140,0000 barrels-per-day Fos-sur-Mer and the 240,000 bpd Port Jerome refineries - which account for 10% and 20% of French refinery output - so far had been little impacted by the strike movement against pension reform.

(Reporting by Geert De Clercq, editing by Louise Heavens)