US Secretary of State Marco Rubio reaffirmed Washington's commitment to Manila and condemned Beijing for its "dangerous and destabilising" actions in the Sea, in his first phone call with Philippine Foreign Secretary Enrique Manalo.

The Philippines will soon decide on an international platform to sue China for alleged damage to the marine environment, its justice minister said, as it pursues a second high-profile legal challenge against Beijing over the South China Sea.

Officials from the Philippines and China have held talks on the disputed South China Sea. Manila expressed "serious concern" over Beijing's deployment of its largest coast guard ship in Philippine waters.

Beijing and Manila have agreed to continue talks on settling their territorial differences despite Philippine protests about the presence of a Chinese "monster ship" near the contested Scarborough Shoal.