IOC had posted a net profit of Rs 3,331.96 crore in the same period a year ago.
The company posted losses "mainly on account of higher absorption of under recoveries on sale of sensitive petroleum products," IOC Chairman R S Butola told reporters here.
IOC absorbed Rs 7,192 crore after the government did not pay full subsidy for selling diesel, cooking gas (LPG) and kerosene at rates lower than cost.
The company had lost Rs 20,697.62 crore on selling diesel and cooking fuel below cost in third quarter this fiscal. The government paid Rs 5,173 crore as cash subsidy and it got another Rs 8,261 crore from upstream firms like ONGC, leaving an unmet gap of Rs 7,192 crore, he said.
But for this, the company would have posted a profit as its interest outgo on debt came down to Rs 1,262 crore from Rs 1,677 crore in third quarter last fiscal. Also, the company made a exchange gain of Rs 1,133 crore as the rupee strengthened against US dollar, he said.
IOC had lost Rs 1,295 crore in foreign exchange in the thidr quarter of last fiscal.
Butola said the company currently loses Rs 7.39 a litre on diesel, Rs 35.76 a litre on kerosene and Rs 656 per domestic cooking gas (LPG) cylinder.
In the first nine months, IOC posted a net loss of Rs 2,370.76 crore after it had to absorb Rs 8,818 crore on fuel sales.
"If we were to have been fully compensated, we would have made a net profit of Rs 6,500 crore in April-December," he said.
Sales rose to Rs 117,415.18 crore in OctoberDecember, 2013 from Rs 116,458.88 crore in the corresponding period a year ago.
The domestic sales of petroleum products fell marginally to 18.169 million tonnes from 18.573 million tonnes.
The company's refineries processed 13.075 million tonnes of crude during October December, 2013 as against 14.208 million tonnes a year ago because of planned maintenance shutdown of some units.
The company earned USD 4.56 on converting every barrel of crude oil into fuel as against a gross refining margin of USD 3.11 per barrel.