China filed more than 73,100 pollution cases last year with total fines exceeding 31.7 billion yuan ($5 billion), an annual increase of 34.4 percent, the national environmental watchdog said on Tuesday.

Cases involving damage to the environment rose by 10.5 percent, 85 percent of which were resolved by year's end, the Ministry of Environmental Protection said, adding that Guangdong and Zhejiang provinces had more than 10,000 cases involving administrative punishments, the highest in the country.

Local environmental protection bureaus at provincial and city level undertook closer cooperation with public security departments to control polluting companies.

Cases involving environmental pollution crimes increased by 300 percent to 2,180 last year, the ministry said.