Courts across the country will continue to hand down harsher punishments to enhance legal awareness and improve environmental and ecological protection of the Yangtze River, China's top court pledged on Thursday.

Since 2016, Chinese courts at all levels, especially those in provinces along the river, have intensified criminal penalties for polluters who seriously damage environmental safety and harm people's health, said Jiang Bixin, vice-president of the Supreme People's Court.

Such acts include individuals and enterprises that discharge pollutants into the river's main streams or branches, illegally transfer dangerous objects or illegally mine sand.

"Tougher criminal punishment as a bigger threat to polluters is a key judicial step to implementing requirements for concerted efforts in river protection," he added.

As of December, courts nationwide had heard 42,230 criminal cases relating to the environmental and ecological protection of the river, offering effective legal services for regional sustainable development, according to Wang Xuguang, presiding judge of the court's environment division.

In a case heard by Sucheng District People's Court in Suqian, Jiangsu province, for example, Yao Duoyou was sentenced to five years and six months in prison and fined 100,000 yuan ($14,400) for polluting the environment, a statement from the top court said.

Thirteen others were given fines and sentences ranging from one year with an 18-month reprieve to 42 months, it said.

The Jiangsu court said that Yao illegally opened a company in Zhejiang to provide technological services for environmental protection and, along with the other defendants, poured and discarded a total of 5,540 metric tons of industrial sludge into ponds in Jiangsu.

"The disposal was done without antipollution measures, and they had no permission to transfer the sludge across provincial borders," Wang said.

"The worst was that the sludge contained lots of heavy metals, including mercury, chromium and arsenic, seriously damaging the environment and ecology."

Although courts have helped fight river pollution in recent years, Wang said legal protections should be strengthened.

He suggested government departments play a stronger role in punishing polluters.

He added that those who turn themselves in or repair the polluted areas could be leniently punished.