Since coming into force on Jan 1, the revised Environmental Protection Law and its supplementary regulations have become increasingly strong factors in the regulation of heavily polluting companies, according to the national environmental watchdog.

In the eight months following the introduction of the revised legislation, fines totaling 328 million yuan ($51.7 million) were imposed on companies that illegally discharged pollutants, and 1,116 cases involving polluting companies were transferred to the judicial authorities for further investigation, the Ministry of Environmental Protection said.

In addition, more than 1,500 companies have been ordered to suspend production or close down completely, and a further 2,400 have seen their production facilities sealed until they upgrade their technology to reduce emissions, a ministry report said.

The revised law, considered China's strictest anti-pollution legislation, stipulates tougher punishments for polluters, including daily, uncapped fines and the transfer of cases to the courts, which can hand down tougher sentences than local authorities.

The revised law gives the environmental protection authorities a wider range of powers to shut down companies with excessive emission levels or to seal their facilities to prevent them from polluting the environment.

Premier Li Keqiang pledged in March to strengthen the implementation of the revised law and to deter polluters by imposing fines that are "too high to bear".

Zou Shoumin, head of the ministry's Environmental Inspection Bureau, said local authorities have adopted special measures this year to enforce implementation, which has proved effective in curbing pollution.

In Hebei province, the environmental and public security authorities have coordinated efforts to punish polluters, and transferred 69 criminal cases to the provincial courts in the first seven months of the year, Zou said.

However, legal challenges by defendants have often made it difficult to impose the tough punishments included in the "revised law with teeth", he added.

For example, a chemical plant in Xianyang, Shaanxi province, which illegally discharged pollutants into the atmosphere and local rivers, refused to pay the 15.8 million yuan fine. Instead, the owners sued the environmental watchdog for "improper law enforcement".

Meanwhile, several cases of forged emissions data have been exposed by frequent inspections, and the companies involved have been punished.