TIANJIN, Aug. 24 (Xinhua) -- The northern Chinese port city of Tianjin has unveiled an action plan to curb pollution in the Bohai Sea, the country's only inland sea.

As more and more industrial firms were set up in regions around the sea in recent years, the Bohai Sea has experienced a deteriorating eco-system.

Local authorities will set a cap on the annual amount of pollutants discharged into the sea and improve environmental monitoring in the coastal waters, according to the three year plan (2018-2020).

Authorities will track the sources of pollutants discharged directly into the sea through sewers, and ensure all industrial pollutants meet environmental standards by 2020.

The plan orders ships to meet standards for waste water discharge and bans them from discharging rubbish and waste oil into the sea.

The plan also bans new chemical raw medicine manufacturers and printing and dyeing firms within one kilometer of the coastline as well as within the main stream of the Haihe River that flows into the Bohai Sea. Existing firms in highly-polluting sectors will either be displaced or upgrade pollution treatment facilities.