PetroChina Co., the listed subsidiary of China's biggest oil and gas producer, reported Wednesday a net profit of 30.8 billion yuan (4.51 billion U.S. dollars) in the third quarter, down 23.2 percent from a year earlier.

Earnings per share were 0.17 yuan, declining 23.2 percent year on year, said the Beijing-based oil producer and refiner Wednesday in a statement to the Shanghai stock exchange. But it did not give specific reasons to the loss.

The company produced 631 million barrels of crude oil in the first nine months, sliding 3.7 percent over the same time last year, while it raised 11.3 percent of its natural gas output to 1.5 trillion cubic meters in the January-September period as the domestic market for natural gas expanded at a quicker pace, according to the statement.

Net profit downward trend was attributed to lower oil prices and weaker energy demand, according to the report.

Shares of the company gained slightly to 13.39 yuan at the closure of Shanghai Composite Index Wednesday.