China has shut down 40 percent of its factories in an unprecedented bid to curb pollution, media reports said Thursday.

The factories were closed in order to be inspected by environmental bureau officials. After the inspections 80,000 factories were reportedly fined and/or charged with criminal offenses for breaching emissions limits.

During this week's Chinese Communist Party Congress, its leadership vowed to step up the fight against pollution, focusing on preventing "major risks," by 2020.

"It will be very difficult to reach the goal, and we need to make greater efforts to achieve it," Chinese environmental protection minister Li Ganjie said Monday.

China also recently announced a plan to reduce the concentration of hazardous fine particulate matter from 47 micrograms per cubic meter to 35 micrograms by the 2035.

According to a report published in the Lancet medical journal, China has the second highest number of pollution-related deaths in the world. More than 1.8 million people die annually from polluted air or contaminated water, meaning nearly 20 percent of premature deaths in China are pollution related.

The Chinese government has been pursuing policies to cut pollution in the country in recent years, actively promoting use of clean energy sources.