China will auction eight shale gas exploration blocks in the first quarter of this year, an expanded plan for China's first such auction, which was originally expected in November, a ministry official said on Thursday.

The auction was originally open to four Chinese energy firms -- PetroChina (0857.HK), Sinopec (600028.SS) (0857.HK), China National Offshore Oil Corp and Shanxi Yanchang Petroleum Group -- but the government has decided to make more companies eligible.

We're adding companies such as Sinochem, Xinjiang Guanghui and Zhenhua which have experience in overseas oil and gas exploration, Zhang Dawei, deputy director of the oil & gas strategy centre at the Ministry of Land & Resources, told Reuters on the sidelines of an unconventional gas conference in Beijing.