Energy giant China National Petroleum Corp (CNPC) will keep drilling through the winter in oilfields in the country's western region to boost domestic crude output as it aims to bolster the nation's energy independence.

Some of CNPC's oilfields in western Chinese regions such as Qinghai, Xinjiang and Shaanxi will not take their usual four-month winter break this year, CNPC's official newspaper said on Thursday, citing a document from the firm's oil engineering and services unit.

Fields in western China typically take such breaks due to harsh winter conditions that make drilling more difficult and expensive. More easterly fields tend to operate year-round.

"CNPC will need to take more forceful measure to boost domestic production as China stresses the importance of energy security," the newspaper said. CNPC is the nation's largest crude oil producer.

China has been pushing to curb its appetite for overseas energy supplies amid trade frictions with the US.

A CNPC official told Reuters that the cost of oil engineering services had fallen to the lowest level in five years, helping make winter production economical.

China's crude oil output climbed in August, ramped up after Chinese leaders called for a boost to national energy security.

Prior to that, output had seen nearly three years of decline.

CNPC's engineering unit, China Petroleum Engineering Corp, will carry out an additional 2 million meters of drilling from November to February, CNPC said via the newspaper.