THE Philippines has accused the China Coast Guard of firing water cannons at two of its vessels, causing damage to one of them, during a patrol near the disputed Scarborough Shoal in the South China Sea, reports German broadcaster Deutsche Welle.

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

"They were not deterred and will persist in carrying out their legitimate operations to support Filipino fishermen and ensure their safety."

The China Coast Guard said the "vessels" had been expelled from waters close to Huangyan Island, which is China's term for the Scarborough Shoal.

One of the vessels belonged to the Bureau of Fisheries and Aquatic Resources (BFAR) and the other was from the Philippine Coast Guard (PCG).

The Filipino boats were delivering fuel and food to fishermen plying the waters near the reef.

"During the patrol, the Philippine vessels encountered dangerous manoeuvres and obstruction from four China Coast Guard vessels and six Chinese Maritime Militia vessels," said the Philippine Coast Guard.

A Chinese vessel used its water cannon, "directly hitting the starboard astern of the BFAR vessel," it added.

The Chinese also targeted the Philippine Coast Guard vessel from both sides, "resulting in damage to the railing and canopy."

China assumed control of the Scarborough Shoal from the Philippines in 2012.

Since then, Beijing has deployed its coast guard and other vessels that Manila says harass Philippine ships and prevent its fishermen from accessing a fish-rich lagoon there.

In 2016, a court ruled that China's historical claims to the area were invalid but Beijing does not recognise the ruling.

China claims almost the entire South China Sea, including parts claimed by the Philippines, Vietnam, Indonesia, Malaysia and Brunei.

The incident comes as the Philippines and the United States hold a major annual military drill that irks China.