BEIJING -- China's ecological environment has deteriorated according to two major pollution indicators in the first half of the year, said an environmental protection official here Friday.

The amount of chemical oxygen demand (COD), used to estimate the amount of organic matter in waste water, rose 4.2 percent while discharges of sulfur dioxide (SO2) up 5.8 percent, said Yang Chaofei, an official with the State Environmental Protection Administration.

The government would impose a stricter system for environmental protection responsibility on officials who would be evaluated on their performance in enforcing protective measures, he said.

Forty percent of China's cities suffer from moderate or heavy air pollution after its rapid economic development over the past two decades.

Li Wenhua, head of China's ecological compensation mechanism and policy research team, said lawmaking was vital to environmental protection.

"The imperative task in China is to define through lawmaking the scope, subjects, methods, compensation standards and set up a transfer payment system favorable to ecological protection." he said.