CNPC employees conduct maintenance work at a gas station in Suining, Sichuan province. 

China National Petroleum Corporation, the country's largest oil and gas producer and supplier, said the company further optimized its production structure last year as it diversifies its business and expands cooperation to meet the country's growing demand for clean energy.

The percentage of natural gas in the company's oil and gas production volume was 51.6 percent last year, and the company has also been actively pushing forward clean energy, including solar power, wind power and hydrogen, it said in a 2021 social responsibility report released on Thursday.

It has come up with 39 new energy projects put into operation in 2021 and newly added new energy development and utilization capacity rose to the equivalent of 3.5 million metric tons of coal last year, it said.

According to CNPC, the company's domestic oil and gas output rose to a record high last year. Newly proved oil geological reserves last year exceeded 1.045 billion tons, and that of natural gas exceeded 1.09 trillion cubic meters, both of which were record highs.

Domestic oil and natural gas output rose 0.8 percent and 5.5 percent year-on-year respectively last year, while overseas oil and gas exploration also rose steadily.

The State-owned energy giant said it would continue to expand natural gas development. At the same time, it will also step up the use of new energy and materials to meet the growing demand for clean and high-quality energy.