China’s recent approval of the “Huangyan Island National Nature Reserve” at Bajo de Masinloc is an illegal encroachment on Philippine sovereignty, the Department of Foreign Affairs (DFA) said Thursday.

The DFA described the move of China’s State Council as a direct violation of international law and a blatant disregard of the Philippines’ sovereign rights.

“Bajo de Masinloc is a longstanding and integral part of the Philippines over which it has sovereignty and jurisdiction,” the DFA said.

“The Philippines likewise has the exclusive authority to establish environmental protection areas over its territory and relevant maritime zones,” it added.

The DFA said the Philippine government will issue a formal diplomatic protest against China’s action, as it called on Beijing to immediately withdraw its pronouncement.

Bajo de Masinloc, also known as Scarborough Shoal, lies 240 kilometers (150 miles) west of the Philippines’ main island of Luzon and nearly 900 kilometers from Hainan, the nearest major Chinese land mass.

China, according to the DFA, must comply with its obligations under international law, particularly the 1982 UN Convention on the Law of the Sea (UNCLOS), the final and binding 2016 South China Sea Arbitral Award, and the 2002 Declaration on the Conduct of Parties in the South China Sea (DoC), the statement said.

On Wednesday, China publicized its move, saying it was reinforcing its territorial claim and maritime rights in the contested region.

The 2016 arbitral ruling, which China has refused to recognize, categorically invalidated Beijing’s sweeping claim over most of the South China Sea, including areas within the Philippines’ exclusive economic zone (EEZ), such as Bajo de Masinloc.

Last month, Manila and Beijing exchanged accusations following a confrontation at Bajo de Masinloc, which led to the first reported collision involving Chinese vessels in the area.

China’s State Council defended its move, claiming the creation of the nature reserve was “an important guarantee for maintaining the diversity, stability, and sustainability of the atoll’s natural ecosystem.”

The council also noted that the specific boundaries and zoning regulations for the reserve will be announced separately by the National Forestry and Grassland Administration.

In asserting its sovereignty over the waters, the Philippines has conducted a series of maritime cooperative activities with like-minded nations like the United States, Canada and Japan within the Bajo de Masinloc.