The failure of the country's two biggest oil producers to meet key environment targets in 2012 has once again put them in the spotlight.

It has also sparked fresh discussions over what kind of social responsibilities our powerful State-owned enterprises should undertake in their painstaking pursuit of bigger market shares.

According to the Ministry of Environmental Protection, China National Petroleum Corporation, the parent of Hong Kong-listed PetroChina, failed to meet its chemical oxygen demand reduction target last year, and China Petrochemical Corporation, or Sinopec, failed to cut nitrogen oxide emissions as required.

The ministry has decided to punish the two corporations by not approving some of their proposed new refining projects or the expansion and renovation of their existing facilities.

In 2012, CNPC reduced chemical oxygen demand 0.08 percent from the previous year, far from the required 0.6 percent cut, while Sinopec witnessed a 1.28 percent rise year-on-year in its nitrogen oxide emissions instead of the required zero growth. According to a notice issued by the ministry, the intensity of chemical oxygen demand in Sinopec's Baling subsidiary, in Hunan province, exceeded the required standard all year long, and nitrogen oxide emissions in its Changling subsidiary, also located in the central province, were 16 times higher than the limit.

CNPC and Sinopec also failed to pass the 2011 pollution assessments made by the environment watchdog and need to step up their emissions reduction efforts.

In sharp contrast, seven overseas oil refiners affiliated to the two oil giants have done much better in terms of emissions control, highlighting that the two companies have adopted different approaches toward their business overseas and at home. Clearly the country's environment watchdog needs to impose and enforce stricter environment standards on their domestic operations and mete out harsher punishments for any violations.

Besides pursuing bigger profits, CNPC and Sinopec should shoulder their social responsibilities and set an exemplary role in energy conservation and greenhouse gas emissions reduction.

The two should be aware that such efforts will help the country realize its commitment to cut energy consumption per unit of gross domestic product by 16 percent from the 2010 level by 2015, and cut chemical oxygen demand and sulfur dioxide emissions by 8 percent, along with other pollutant cuts.