PetroChina Co Ltd's third-quarter net profits grew 21 percent year-on-year, a record high, thanks to increased output and improving domestic fuel demand, the company said on Monday.

Net profit for the country's biggest oil company during the third quarter rose to 46.38 billion yuan ($6.3 billion), following a record profit in the first half as the company increased output.

Crude oil output during the first nine months rose 4.3 percent year-on-year to 706 million barrels, while natural gas output grew 6.1 percent to 3,656.6 billion cubic feet, it said.

The company seized the opportune timing of recovery in Chinese macro economy and rebounds in oil and gas markets this year, which contributed to the record growth, it said.

Total fuel sales, including gasoline, diesel and jet kerosene, rose 13.4 percent year-on-year at 125.6 million tons, including domestic sales at 93 million tons, up 17 percent year-on-year.

Capital spending reached 174 billion yuan during the first nine months, up 10 percent compared with the same period of the previous year, it said.