BEIJING -- Chinese oil giant PetroChina Co said Tuesday that its net profit in the third quarter tumbled 33.4 percent from a year earlier to 24.93 billion yuan ($3.96 billion).

The contraction in the third quarter was sharper than the 6-percent decline recorded in the first half of this year.

In a statement filed with the Shanghai Stock Exchange, PetroChina attributed the contraction in net profit to increased imported natural gas, heavy losses in the refinery business and the price formation mechanism that is strictly controlled by the state in the domestic market.

In the July-September period, the oil giant's business revenues rose 3.95 percent year-on-year to 551.61 billion yuan, with its earnings per share standing at 0.14 yuan, compared with 0.2 yuan in the same period of last year, it said.

For the first nine months of this year, PetroChina's net profit dropped 15.9 percent year-on-year to 86.96 billion yuan.

The company's crude oil output rose 2 percent year-on-year to 683.2 million barrels, while the volume of processed crude oil amounted to 743.5 million barrels, up 2.5 percent from a year ago.

Meanwhile, due to weak domestic demand and government price controls, PetroChina's refining and chemicals business posted losses of 37.4 billion yuan.

The company's overseas oil and natural gas output increased 7 percent from a year earlier to 99.5 million barrels of oil equivalent.

The third-quarter performance consolidated PetroChina's position as China's most profitable oil giant in the first nine months of this year, beating Sinopec's net profit of 42.83 billion yuan.

China National Offshore Oil Corporation Limited, the country's largest offshore oil producer, listed in Hong Kong, has yet to update its third-quarter results, but it is believed it will be unlikely to exceed PetroChina since its net profit amounted to 31.87 billion yuan in the first half of this year.

Listed in both Hong Kong and Shanghai, PetroChina is a listed subsidiary of China National Petroleum Corporation, China's largest oil and gas producer.

The share price of PetroChina added 0.37 percent to HK$10.8 ($1.394) in Hong Kong and 0.34 percent to 8.74 yuan in Shanghai on Tuesday.