BEIJING - China's supreme court and procuratorate jointly issued a new judicial explanation Tuesday that imposes harsher punishments on polluters.

The new legal document confronts difficulties in investigating cases of environmental pollution and in convicting polluters, according to a statement issued by the two judicial departments.

With more precise criteria for convictions and sentencing, the document is expected to facilitate the work of judges and tighten punishments for polluters, it said.

The document lists 14 sorts of activities that will be considered "crimes of impairing the protection of the environment and resources."

For instance, discharging, dumping or treating radioactive waste or waste containing infectious disease pathogens or toxic substances into sources of drinking water and nature reserves will be considered crimes of polluting the environment.

Activities that result in pollution that forces more than 5,000 people to be evacuated or poisons more than 30 people are also considered environmental pollution crimes.

Those who pollute near hospitals, schools and large residential areas will be considered serious offenders.

According to the country's Criminal Law, those convicted of such crimes will face a maximum prison term of seven years and be subjected to fines.

In China, more than 10 million hectares of farmland have been polluted, and heavy metals and pesticide residues that people ingest through food will greatly threaten public health, said Qian Guanlin, a senior national political adviser.

"Environmental pollution is a major cause of the high incidence of cancers in China," said Qian, vice-director of the population, resources and environmental committee under the National Committee of the Chinese People's Political Consultative Conference (CPPCC).