CNOOC Ltd, China's biggest offshore oil and gas producer, posted a 15 percent fall in third-quarter sales as output declined with capital spending. Its shares led declines among energy companies in Asia on Thursday.

Revenue from oil and natural gas was 30.75 billion yuan ($4.5 billion) in the three months ended on Sept 30, the Beijing-based company said in a statement to the Hong Kong stock exchange on Wednesday. CNOOC, which doesn't report quarterly profit, said output fell 7.7 percent.

CNOOC fell as much as 3.4 percent in Hong Kong on Thursday before trading down 3.1 percent at HK$10.16($1.31) at 9:57 am local time. The city's benchmark Hang Seng Index slipped 0.5 percent, while the MSCI Asia Pacific AP Energy Index lost 0.9 percent.

"CNOOC's sales decline was well-expected as oil prices haven't rebounded to a level that may push the offshore producer to increase output," Tian Miao, a Beijing-based analyst at North Square Blue Oak Ltd said."Fourth-quarter output should be similar to the third-quarter, and CNOOC may continue to pay a high dividend to please shareholders in the low crude price environment."

Brent oil, the global benchmark, averaged $46.99 a barrel in the third quarter, an 8.4 percent decline from the same period last year. The company's realized oil price during the quarter fell 13.5 percent from the previous period, while the natural gas price tumbled 18.6 percent.

Output declines in the third quarter were caused by oilfield maintenance, bad weather and a lack of new projects, chief financial officer Zhong Hua said in a conference call after the earnings were released.