State-run Indian Oil Corp, the country's largest refiner, shut the cracking unit of its 274,000-bpd Koyali refinery in Gujarat state after a blast on Friday, but hopes to restart in a week, a company spokesman said.
It was not immediately known what caused the blast at the fluidised catalytic cracking unit (FCCU) at the refinery, Indian Oil's largest, the spokesman said, adding it had been shut for maintenance this month.
Police said 16 workers had been taken to hospital.
"It was a minor blast that hit the FCCU while restarting after a scheduled maintenance. The fire was brought under control immediately. The rest of operations are normal," the spokesman said.
A company spokesman told Reuters it would take at least a week to restart the FCCU.
"We have already started repair work. But it could take at least a week to operationalise as some spares and equipment will have to be requisitioned," the spokesman said. He had earlier said the FCCU could be restarted in 2-3 days.
A senior IOC official told Reuters the fire had reduced crude throughput by 25-30 percent.