The Philippines is assigning names to land features at a vast underwater plateau on its continental shelf, ignoring the fact that China has named four seamounts and a hill in the area.
"When it comes to naming, there is a process to be followed in line with the UN system. It's not a political process, but scientific. Whoever discovered (the land features) gets to name them," Mr Harry Roque, the spokesman for President Rodrigo Duterte, said at a news briefing yesterday.
The United Nations recognised the Philippines' exclusive economic rights to the underwater landmass - known formerly as Benham Rise and renamed Philippine Rise - in 2012 as part of its continental shelf.
Philippine Rise is believed to be rich in tuna, natural gas and steel-producing resources like manganese.
At 130,000 sq km, or roughly the size of the Malaysian peninsula, and largely unexplored, Philippine Rise sits 250km east of the main island of Luzon, along the path of at least a dozen storms and typhoons that move across the archipelago each year. It is also 2,000m to 5,000m deep.
These conditions have prompted the Philippines to ask other nations, including China, to help it map and survey the area.
China submitted the names for five features at the Philippine Rise to a special naming subcommittee of the International Hydrographic Organisation in 2015 and 2017. These are for seamounts - underwater mountains - and a hill. China designated them as Jinghao, Tianbao, Haidongquing, Cuiquiao and Jujiu, which form the central peaks of the underwater landmass.
The Philippines has already complained about China's move, amid concerns Beijing may be claiming more maritime territory.
Mr Duterte last week demanded that other nations cease all scientific missions and exploration at the Philippine Rise after "a low-level diplomat of another country" suggested that the underwater landmass did not belong to the Philippines.
The diplomat was not identified, but a Chinese Foreign Ministry spokesman said last year that Manila could not claim the Philippine Rise as part of its territory.
China's foray into Philippine Rise has caused concerns among nationalists in the Philippines, mistrustful of Chinese intentions after decades of disputes and perceived encroachments by Beijing in the South China Sea.
Philippine Rise is not in the South China Sea, and Beijing has made no claim to it.
Analysts have also suggested that China's scientific research in the area could be part of a larger effort to create a second "fence" east of the South China Sea to further challenge US dominance in the Pacific.
Philippine Rise sits near US military bases in Guam and Hawaii, and there have been concerns China could be testing water depths for submarine routes from the South China Sea to the Pacific.