BEIJING - Chinese police have detained 118 suspects involved in environmental pollution cases since January, the Ministry of Public Security announced on Tuesday.

Of the total, 24 suspects in four major cases have been charged by prosecutors and are awaiting trial, said a ministry statement.

There have also been breakthroughs in investigations into other cases, it added.

Most of these pollution cases involved mining or petrochemical factories. Some, including a number of large factories, discharged toxic substances into the environment illegally, while others used illegal middlemen to sell toxic waste to companies or individuals that were not qualified to process the waste, the statement said.

Some of these polluters are big taxpayers and have gained support from local governments, it added.

Early this year, the ministry launched a national campaign against crimes that result in environmental pollution.

Also on Tuesday, China's supreme court and procuratorate jointly issued a new judicial explanation that aims to reduce difficulties in investigating cases of environmental pollution and in convicting polluters.