Philippine President Rodrigo Duterte said he has ordered troops to deploy on unoccupied South China Sea islands and reefs claimed by Manila, in a move that could provoke rival claimants including Beijing.

"It looks like everybody is making a grab for the islands there, so we better live on those that are still vacant," he told reporters during a visit to a military camp on the western island of Palawan, near the disputed Spratly group.

China asserts sovereignty over almost all of the resource-rich South China Sea despite rival claims from Southeast Asian neighbors and has rapidly built reefs into artificial islands capable of hosting military planes. Vietnam, Malaysia, Brunei and Taiwan have also sparred with Beijing over territory in the disputed waterway. US President Donald Trump's administration so far has taken a tough stance on China's claims in the South China Sea, insisting it will defend international interests there.

Duterte has previously sought to improve his nation's relations with China by adopting a non-confrontational approach over their competing claims in the strategically vital waters. But the president appeared to alter his tone with his announcement Thursday, saying it was time to "erect structures there and raise the Philippine flag." "I have ordered the armed forces to occupy all.

Duterte also said he "may" visit the Philippine-claimed areas on June 12 to mark Philippine Independence Day.