Manila says it has sent a patrol vessel to stop Beijing building an island in a hot spot in the South China Sea.

A spokesperson for the Philippine Coast Guard said it found crushed corals piled up on the seabed at Sabina Shoal in the Spratly Islands. He said it's highly likely China dumped the material as landfill.

Footage taken by the coast guard in shallow waters at the shoal shows a large white mound on the seafloor.
It's noticeably lighter than the surrounding reef.
The coast guard says Chinese ships have been present in the area.

The shoal is 140 kilometers from the western Philippine island of Palawan -- well inside the country's exclusive economic zone.
The Chinese foreign ministry dismissed Manila's claim, calling it "groundless and fabricated." It said the Philippines "has repeatedly spread rumors and deliberately smeared China in a vain attempt to mislead the international community."

Manila said in March it found Beijing carrying out similar reclamation work in another area of the South China Sea.