Two Chinese surveillance ship fleets have arrived waters around Diaoyu Islands and its affiliated islands Friday and started patrol and law enforcement there.

China marine surveillance ship. [File photo]

It is the first time for Chinese surveillance ships to patrol there after the Chinese government announced on Monday the base points and baselines of the territorial waters of the Diaoyu Islands and their affiliated islets, as well as the names and coordinates of 17 base points.

These law enforcement and patrol activities are aimed to demonstrate China's jurisdiction over the Diaoyu Islands and its affiliated islets and ensure the country's maritime interests, according to a government statement.

Chinese Assistant Foreign Minister Le Yucheng said Friday these countermeasures by the Chinese government are an effective way to further uphold and strengthen China's sovereignty over the Diaoyu Island and its affiliated islands.

Le made the remarks when addressing a seminar on the Diaoyu Islands at the Diaoyutai State Guesthouse.

He said China delimited and published the base points and baselines of the territorial sea of the Diaoyu Island and its affiliated islands in accordance with the Law of the People's Republic of China on the Territorial Sea and the Contiguous Zone.

"This is in line with the UN Convention on the Law of the Sea (UNCLOS)," said Le.

On the same day, China's permanent representative to the United Nations Li Baodong met with UN Secretary-General Ban Ki-moon Thursday (local time) and filed a copy of the table of coordinates and charts of the baseline of the Diaoyu Island and its affiliated islands.

An official with the Ministry of Agriculture Thursday said that China would conduct routine patrols near the Diaoyu Islands to assert the country's sovereignty and protect fishermen.

The Diaoyu Islands and their affiliated islets have been China's inherent territory since ancient times, and their surrounding waters are China's traditional fishing grounds, according to the ministry.

Data showed that over 1,000 Chinese fishing boats enter the waters of the Diaoyu Islands each year, with their total catch exceeding 150,000 tonnes.

However, increasing harassment from Japanese ships in recent years has severely affected China's fishing activities, triggering widespread protest and condemnation of Japan.

In order to safeguard the interests of China's oceanic fishing industry and ensure safety for Chinese fishermen, the ministry has asked fishery authorities in Zhejiang and Fujian provinces to include areas surrounding the Diaoyu Islands in their regular patrol scopes, the official said.