This image shows the outer limits (in purple) of the Philippine continental shelf beyond 370 kilometers in the West Palawan region.

MANILA — China has filed a protest against the Philippines’ request to extend its continental shelf claim in a United Nations body.

In a note verbale dated June 18, China appealed to the UN Commission on the Limits of the Continental Shelf “not to consider” the submission filed on June 14 by the Philippines, which invoked its right under the UN Convention on the Law of the Sea (Unclos).

 “China has indisputable sovereignty over Nanhai Zhudao and the adjacent waters, and enjoys sovereign rights and jurisdiction over the relevant waters as well as the seabed and subsoil thereof,” the diplomatic communication read.

Nanhai Zhudao, or the “South China Sea islands,” are claimed by several countries in the region, including the Philippines, Vietnam, Malaysia, and Brunei.

Beijing said that the extended continental shelf beyond 370 kilometers (200 nautical miles) contained in the Philippines’ submission “seriously infringed” on China’s sovereignty, sovereign rights, and jurisdiction in the South China Sea.

Hanoi said on Friday it was willing to talk to the Philippines to seek measures that were in line with the interests of both countries after Manila last week filed its extended continental shelf claim.

“Vietnam once again affirms its sovereignty over the Hoang Sa and Truong Sa archipelagos in accordance with international law,” foreign ministry spokesperson Pham Thu Hang said in a statement posted on a government website, referring to the Paracel and Spratly Islands.

Almost the entire South China Sea, a busy global maritime waterway, is claimed by China.

This claim has been invalidated by an international arbitral tribunal, saying that Beijing had no legal basis over it.

About $3 trillion worth of annual trade passes through the strategic waterway, which is believed to be rich in oil and natural gas deposits as well as fish stocks.

“Coastal states, when submitting their outer continental shelf boundaries, need to respect the legitimate rights and interests of other relevant coastal states with opposite or adjacent coastlines,” Hang said in the statement.

Maritime law expert and retired Supreme Court Senior Associate Justice Antonio Carpio advised the Philippine government to accept the standing invitation of Vietnam and Malaysia to submit their overlapping extended continental shelf claims in the southern area of the South China Sea to voluntary arbitration under Unclos.

 “The Philippines should invite China to join in the voluntary arbitration if China believes it has a claim over the same area. This will ensure a peaceful settlement of the maritime dispute in accordance with the UN Charter and Unclos,” Carpio told the Inquirer.

Foreign Assistant Secretary Marshall Louis Alferez said last week that the Philippines’ submission was a step toward discussing boundary issues and future cooperation with other nations.

It also showed respect for ongoing discussions with other coastal states that might have valid claims under Unclos.

“What is important is [that] the Philippines puts on record the maximum extent of our entitlement,” Alferez said.

Unclos defines continental shelf as the submerged extension of a coastal state’s land territory covering the seabed and subsoil beyond its territorial sea up to the edge of its 370-km exclusive economic zone.

Article 76 of Unclos allows the coastal state to extend the outer limits of its continental shelf to a maximum of 648 km (350 nautical miles) from the baselines of its territorial sea.

Article 77 grants coastal states sovereign rights over natural resources found on or beneath the continental shelf, including minerals and other nonliving matter, as well as organisms that are fixed to the seabed or subsoil.