Italian emergency services have ordered local residents to stay inside their home.
The Italian Department of Civil Protection in the province of Alessandria said in a statement "The fire occurred inside refinery Italian ENI energy company occurred around 15:40 (local time), causing a large fireball of tens of meters."
Eni, Italy's biggest refiner, said in a statement the fire had started at around 4.00 pm in the so-called EST plant at the refinery. The cause was still unknown. MORE