Net profit for the period reached 43.62 billion yuan ($6.3 billion), the company's statement said, ahead of the 38.9 billion yuan a year earlier and well above Refinitiv estimates of 33.77 billion yuan.

Quarterly revenue was down 6% at 732 billion yuan.

Total crude oil output increased 5.1% year on year to 236.3 million barrels while gas output rose 4.7% to 1,294 billion cubic feet.

PetroChina, which is also China's second-largest oil refiner, processed 8.1% more crude oil than a year ago at 326.9 million barrels in the first three months of the year, equating to 3.63 million barrels per day (bpd), thanks largely to a refinery launched in southern China last October.

Highlighting rebounding domestic fuel consumption, PetroChina's aviation fuel and diesel output grew 32.7% and 10.7% respectively, though gasoline was down 4.4%.

The company took advantage of China's demand recovery, it said in a Hong Kong Stock Exchange filing, and worked on marketing, market expansion and inventory reduction to boost profit.

Natural gas sales also benefitted from recovering industrial activity, with volumes up 2.9% and operating profit climbing by 13.3% year on year.

"The group's operating results maintained growth and its financial condition stayed healthy, although the international oil price decreased compared with the same period last year," its stock market filing said.

($1 = 6.9191 Chinese yuan renminbi)

(Reporting by Chen Aizhu in Singapore and Dominique Patton in Beijing; Editing by David Goodman)