Philippine officials say they received two intimidating radio warnings from people who identified themselves being from the Chinese navy when they flew a Cessna plane close to a Chinese-constructed island in the South China Sea.

Eric Apolonio said the incident happened Jan. 7 when he and other personnel of the Civil Aviation Authority of the Philippines flew to a Philippine-occupied island for an engineering survey ahead of the planned installation of aviation safety equipment on the island.

The island, which the Philippines calls Pag-asa, is close to Subi Reef, which has been transformed by China into an island in the disputed Spratly chain.

Apolonio said the voice message warned that the aircraft was "threatening the security of our station." He said they continued their trip.