BEIJING (REUTERS) - China's environment ministry will stop approving some new refining projects or the expansion or renovation of existing facilities by the country's top state-owned oil firms after they failed to meet key pollution targets in 2012, it said on Thursday.

The ministry said China National Petroleum Corporation (CNPC) failed to meet targets to cut chemical oxygen demand in 2012, while Sinopec Group failed to meet a target to cut nitrogen oxide emissions.

CNPC is the parent of PetroChina, China's dominant oil and gas producer. Sinopec Group is the parent of top Asian refiner Sinopec Corp .

The Ministry of Environmental Protection said in a notice posted on its website (www.mep.gov.cn) that according to its regulations, it would stop approving environment impact assessments for all new refining projects from the two companies, apart from those that concern fuel product upgrades or environmental renovations.