PSO imports between 85 and 90 percent of the country's fuel oil and petrol, but it has been forced to cut purchases because it has not been paid by its customers.
The tender to buy 10 65,000-tonne high sulphur grade cargoes was awarded at premiums ranging from $21 to $26 a tonne to Middle East fuel oil quotes, on a free-on-board (FOB) basis.
The company also bought three 60,000-tonne low-sulphur grade cargoes at premiums in the range of $48 to $55 a tonne to Middle East fuel oil quotes.
Sellers were Chinese major PetroChina, Azerbaijan's Socar, and traders including Swiss Singapore, Al-Ghurair Energy, Gulf Petrochem, Vitol.
About a third of Pakistan's electricity is powered by fuel oil.
Separately, PSO had bought a total of 500,000 tonnes of gasoline for March to May delivery at premiums of about $71 to $88 a tonne to Middle East naphtha quotes, on a FOB basis.
Sellers of the motor fuel are predominantly PetroChina, which will supply five 50,000-tonnes cargoes, followed by Gunvor with 100,000 tonnes. Vitol, Oman Trading and Swiss Singapore will each supply 50,000 tonnes.