China has accused the Philippines of trespassing in waters adjacent to Scarborough Shoal, which Beijing refers to as Huangyan Dao, "without the approval of the Chinese government."

In a statement on Monday, Air Force Senior Col. Tian Junli, the spokesperson for the Chinese People's Liberation Army Southern Theater Command, said a Philippine frigate "trespassed" into their territory.

According to Tian, the naval and air forces of the Chinese PLA Southern Theater Command "tracked, monitored, warned, and restricted the Philippine military vessel according to the law."

China said the Philippines' action "seriously violated China's sovereignty, international law and basic norms governing international relations, and was highly likely to cause misunderstanding and miscalculation."

"We urge the Philippine side to immediately stop its infringement and provocation to avoid further escalation," he said.

The Philippines brushed aside China's accusation of trespassing.

National Security Adviser Eduardo Año on Tuesday said the Philippine frigate could not have trespassed in Scarborough Shoal as it is, "in fact, part of the country's exclusive economic zone" located in the West Philippine Sea.

Año slammed China's admission that its vessels had been shadowing Philippine ships conducting legal maritime operations in the WPS, like the Philippine Navy's BRP Conrado Yap.

"China is again overhyping this incident and creating unnecessary tension between our two nations," he said. "Under international law, the Philippines has every right to patrol the length and breadth of the West Philippine Sea, which necessarily includes Bajo de Masinloc."

                                                                                                                      Not deterred

Año said the Armed Forces of the Philippines and the Philippine Coast Guard will not be deterred by the "aggressive and illegal activities" of either China's People Liberation Army Navy, China Coast  Guard, or Chinese Maritime Militia in the WPS.

"The Conrado Yap conducted routine patrol operations in the general vicinity of Bajo de  Masinloc without any untoward incident. It did not illegally enter any space under Chinese sovereignty because Bajo de Masinloc is part of the Philippine archipelago and EEZ," he stressed.

Año urged China "to act responsibly, respect the United Nations Convention on the Law of the Sea and adhere to the 2016 arbitral ruling in favor of the Philippines in its claim to the WPS, as well as to promote the rules-based international order."

He called on China to "stop its aggressive and illegal actions in Philippine waters."

"Following the strong guidance of President Ferdinand Marcos Jr., we will protect our territory and sovereign rights at all costs," Año said.

AFP spokesperson, Col. Medel Aguilar, backed Año's statement, saying the Philippines did not illegally enter the Bajo de Masinloc.

Legitimacy

"An illegal occupant cannot prevent the legitimate owner from entering his own house and backyard," Aguilar told reporters in a Viber message.

Philippine officials have repeatedly emphasized that Scarborough Shoal, or Bajo de Masinloc, is located 124 nautical miles east of Zambales, within the Philippine archipelago.

China claims the vast South China Sea, including the West Philippine Sea.

The 2016 Arbitral Award on the South China Sea, however, invalidated Beijing's historic nine-dash line claim in the area, which is also a shipping passage for $5.3 trillion worth of trade annually.

Seven years after the Tribunal favored the Philippines' arbitral case against China, the ruling remains on paper as China continues to disregard it by holding military activities in the West Philippine Sea.