Fire brigade personnel from Surat and nearby cities were trying to bring the fire under control.
Hazira facility of IOC has nine storage tanks, five of petrol and four of diesel.
One of the tanks caught fire this afternoon, and it spread.
There were no reports of any casualties as yet, while all the staff members have been shifted out.
The Hazira terminal includes a deep water multi-cargo port, situated 25 km from Surat.
The blaze could be seen from afar, local sources said.