Manila, Philippines - The Philippines said the China Coast Guard on Tuesday fired water cannons at two of its vessels, causing damage to one of them, during a patrol near a reef off the Southeast Asian country.

The incident happened near the China-controlled Scarborough Shoal, which has become a potential flashpoint in the disputed South China Sea, during a mission to resupply Filipino fishermen.

"This damage serves as evidence of the forceful water pressure used by the China Coast Guard in their harassment of the Philippine vessels," a statement issued by the Philippine Coast Guard said.

The China Coast Guard had reinstalled a 416-yard barrier across the entrance to the shoal – a traditional fishing ground – blocking access to the waters inside, the statement said.

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The triangular chain of reefs and rocks lies 150 miles west of the Philippines' main island of Luzon and some 550 miles from the nearest major Chinese land mass of Hainan.

China seized the shoal from the Philippines in 2012 and has since deployed coast guard and other vessels that Manila says harass Philippine ships and prevent its fishermen from accessing a fish-rich lagoon there.

Beijing claims almost the entire South China Sea, brushing off rival claims from other countries, including the Philippines, and an international ruling that says the claim has no legal basis.

This latest incident comes as the Philippines and the US hold a major annual military exercise that has increased tensions in the region.