NEW DELHI - State-run Indian Oil Corp expects to re-open its 40,000 bpd crude unit by end-December after a maintenance shut down at its Koyali refinery in western Gujarat state, a company source said on Friday.

The unit and its attached downstream units were shut from Nov. 27, months later than the planned August-September shutdown.

We rescheduled the shutdown to November to meet fuel demand in August-September. Our FCCU is also shut for maintenance, the official, who did not wish to be identified, added.

The 274,000 bpd Koyali plant in Gujarat is IOC's biggest refinery and has one fluid catalytic cracker unit (FCCU) with an annual capacity of 1.8 million tonnes.

IOC, the country's largest oil refining and marketing firm, operates about 10 refineries across India with a total capacity of 1.204 million bpd. (Reporting by Nidhi Verma; Editing by Malini Menon)