China has publicized for the first time what it claims is an unwritten 2016 agreement with the Philippines over access to South China Sea islands.

Two senior Philippine officials on Sunday denied a claim by China that Manila had agreed on a “new model” in handling their territorial dispute in the South China Sea.

The injuring of Filipino crew and damage to Philippine vessels in the South China Sea is "irresponsible behaviour and disregards international law", U.S. Defense Secretary Lloyd Austin told a joint press conference on Thursday.

China alleges that in 2016, the Philippines entered into an unwritten agreement that restricted access by military and other official ships to islands in the South China Sea.

The Philippines summoned a Chinese diplomat on Thursday to protest Beijing's use of water cannon against Filipino vessels at a disputed shoal in the South China Sea, describing it as harassment and "dangerous manoeuvres".