The sole state-run Eastern Refinery Limited will remain closed for 35 days for its overhauling.
The shutdown started on November 16 as all the units of the company will be under maintenance during this period, said an official.
Besides, larger parts of the machineries will be opened up for cleaning and old parts of oil refineries will be replaced with new ones during this time, according to him.
"It is a scheduled shutdown for overhaul every two years. We notify the BPC to keep sufficient reserves of fuel oil beforehand. We usually go forward with the shutdown after we receive the approval of the BPC. So, there will be no shortage of fuel," he said.
According to the BPC, there is a daily demand of around 800 tonnes of octane, 800 tonnes of petrol and 11,000 tonnes of diesel in the country.
The BPC has a reserve capacity of around 13 lakh tonnes of fuel oil, including six lakh tonnes of diesel.
