The delimitation and declaration of the baselines of the territorial sea adjacent to Huangyan Dao is a natural step by the Chinese government to lawfully strengthen marine management, the Foreign Ministry said on Sunday.

It is consistent with international law and common practices, the ministry said in an online statement.

A spokesperson stressed in the statement that Huangyan Dao has always been China's territory.

The baselines of the territorial sea adjacent to the island was delimited and announced in accordance with international law, such as the United Nations Convention on the Law of the Sea, and the Law of the People's Republic of China on the Territorial Sea and the Contiguous Zone, the spokesperson said.

The announcement came two days after the Philippines enacted the so-called Philippine Maritime Zones Act, which the Chinese spokesperson said severely violates China's territorial sovereignty and maritime rights and interests in the South China Sea.

The Philippine act aims to further solidify the illegal arbitral award on the South China Sea in the form of domestic legislation and illegally include China's Huangyan Dao and most of the islands and reefs of China's Nansha Islands, and their relevant waters into the Philippines' maritime zones, the spokesperson said.

China firmly opposes it and will continue to do everything necessary in accordance with law to firmly defend its territorial sovereignty and maritime rights and interests, the spokesperson added.