More than 4,000 factories using heavy metals have closed in China in the past three years, cutting production of millions of tons of batteries containing copper, zinc and lead.

Central and local governments spent 41.6 billion yuan ($6.7 billion) in the past three years to prevent and treat heavy metal pollution, and the emission of pollutants has been greatly reduced, the Ministry of Environmental Protection revealed at a meeting on Sept 2.

Environmental issues have also led to the temporary closure of over 1,000 companies, which will be allowed to reopen when their situations are rectified.