China has breached international obligation with its alleged continuous activities in the disputed South China Sea, including landing of its transport planes in Panganiban Reef, Malacanang said on Thursday.

In a press briefing, Presidential Spokesperson Harry Roque echoed the statement of Foreign Affairs Secretary Alan Peter Cayetano the government is preparing and exploring the possibility of a diplomatic protest following a news report two Chinese cargo planes were seen in Panganiban Reef, an area within the exclusive economic zone of the Philippines.

"Obviously if we consider a diplomatic protest, then you consider the other state to be in breach of an international obligation… somehow," he said.

The Philippines and other Southeast Asian countries, which have claims in South China Sea, have been consistently asking China not to militarize the disputed waters.

They are also working with China a binding and enforceable Code of Conduct in South China Sea. Celerina Monte/DMS