The Nigerian National Petroleum Corp. says it lost 267 billion naira ($1.3 billion) in 2015, even as it tried to pump more oil to counter slashed world prices.

The corporation's monthly report posted at its website Thursday shows the biggest losses recorded at its headquarters, by three refineries and a subsidiary that sources and distributes refined products. Nigeria is Africa's biggest oil producer but imports most refined products because its refineries are inefficient.

Petroleum production averaged 1.6 million barrels a day last year with swings from a million barrels to 2.5 million barrels a day. Oil accounted for 70 percent of government income.

Profits came from the Nigerian Gas Co., 34.9 billion naira ($175 million) and from oil and gas exploration and production, 16.9 billion naira ($85 million) in 2015.