MANILA — The Philippine government protested on Thursday the presence of large numbers of Chinese vessels near islands and islets occupied by the Philippines in the disputed South China Sea as illegal and vowed to take ‘‘appropriate action.’’
The Department of Foreign Affairs issued the rare public rebuke of the Chinese presence after the Philippine military monitored more than 200 Chinese vessels from January to March in a disputed area named Sandy Cay near a Philippine-occupied island called Pag-asa by Filipinos.
‘‘The presence of Chinese vessels near and around Pag-asa and other maritime features . . . is illegal,’’ the department said in a statement. ‘‘Such actions are a clear violation of Philippine sovereignty, sovereign rights, and jurisdiction as defined under international law.’’
The department said it has lodged diplomatic protests and raised concerns in meetings with Chinese officials, and that the presence of Chinese military, fishing, or other vessels in the area would ‘‘continue to be the subject of appropriate action by the Philippines.’’
The Philippines regards a chain of islands and islets, nine of which it occupies, in a contested region named the Spratlys in the South China Sea as a municipality it calls Kalayaan under its western province of Palawan. That claim conflicts with the larger territorial claims of China, Vietnam, and three other governments in a long-simmering Asian dispute.
A 2002 accord between China and the 10-nation Association of Southeast Asian Nations aims to prevent armed confrontation in the busy waterway, where much of Asia’s oil and trade transits.
Chinese boats have swarmed around Sandy Cay, a chain of three sandbars that naturally emerged in recent years, since 2017. The sandbars lie between Pag-asa, which is internationally called Thitu, and a Chinese man-made island called Subi.
The Philippines tried to occupy the largest sandbar, about 2.5 nautical miles from Thitu, in 2017 but China strongly protested.