China is proposing to host the secretariat of a new treaty governing the high seas.

China "has decided to present its candidature of the city of Xiamen to host the Secretariat" of the treaty, the Chinese mission to the United Nations wrote in a letter to Secretary-General Antonio Guterres on Friday.

The treaty will officially enter into force on Saturday, and the host country of the eventual secretariat will be decided this year.

Until now, Belgium and Chile had been vying to host the future organisation.

China's announcement came just days after US President Donald Trump announced the US would withdraw from 66 global organisations and treaties – involving UN and non-UN entities.

They include the United Nations Framework Convention on Climate Change, the parent treaty underpinning all major international climate agreements, ratified by almost every country in the world.

After years of delays, the treaty to protect the high seas was ratified in September by 60 countries. The law aims to protect biodiverse areas in waters worldwide, extending beyond countries' exclusive economic zones. (AFP)