CNOOC Ltd's net profit fell 11.4 percent to 56.46 billion yuan ($9.11 billion) last year, even as output set records, the company said on Friday.

CNOOC, China's largest offshore oil and natural gas developer, said the decline mainly reflected higher costs and lower realized oil prices.

"The decline was caused by a weak upstream crude market. Also, the company doesn't have a strong presence in the oil products retail market compared with the other two giants - PetroChina Co and Sinopec Group," said Wang Yanting, oil product analyst at consultancy JYD Online Corp.