BEIJING — Chinese authorities had issued more than 20,000 pollutant emission permits by the end of 2017, an official from the Ministry of Environmental Protection said.

The permits were granted to companies nationwide in 15 sectors including steel, iron, and cement, said the ministry, which started reforming the permit system in 2016 to better protect the environment.

If a company is caught discharging pollutants without a permit, it could be required to suspend production or shut down, and faces a fine of up to one million yuan ($157,000), according to a policy document which was published earlier.

Companies guilty of other violations including excessive emissions and falsifying monitoring data will also face similar penalties of closure and heavy fines.

The ministry will continue improving the legal standards and technological system of the emission permit system and formulate norms and standards for the application and approval of emission permits for other major industries, said Liu Youbin, spokesperson for the ministry.

China’s policy makers have listed fighting pollution as one of the country’s “three tough battles” for the next three years, along with risk prevention and poverty alleviation.

Another move is collecting an environment tax, as China’s Environmental Protection Tax Law took effect on Jan 1, 2018.