CNOOC Ltd., China's biggest offshore oil and gas producer by output, is going ahead with two big coal-to-natural gas projects in China, Chairman Fu Chengyu said Saturday.

He said the two projects would have a combined annual output capacity of 10 billion cubic meters of gas within five years.

Fu confirmed that one of these two projects was a venture with Datong coal Mine Group, in Shanxi province.

The other, he said, was based in the autonomous region of Inner Mongolia, but he wouldn't give any details or the name of a partner in this second project.

In April this year, an executive with CNOOC Group, the parent of CNOOC Ltd., said the company had signed a cooperation agreement with Datong Coal Mine Group to build in Shanxi province a coal gasification plant with a planned investment of 30 billion yuan ($4.4 billion).

The plan, details of which were still to be finalized, is expected to produce around 4 billion cubic meters of gas a year when fully operational, the CNOOC Group executive said.

On April 10, Xinhua New Agency reported CNOOC's rival, PetroChina Co., planned to invest 1.58 billion yuan in 2009-10 to develop reserves of 408 billion cubic meters of coal seam gas in Hancheng city, northern Shaanxi province.