China claims almost the entire South China Sea, brushing off rival claims from other countries -- including the Philippines -- and an international ruling that its assertion has no legal basis.
Video released by Manila on Wednesday appeared to show a China coast guard ship hitting the right side of the BRP Datu Pagbuaya, a fisheries department vessel, with the crew shouting, "Collision! Collision!".
The Chinese ship "fired a water cannon... aiming directly at the vessel's navigational antennas", Philippine coast guard spokesman Commodore Jay Tarriela said in a statement.
The Chinese vessel then "intentionally sideswiped" the ship before launching a second water cannon attack, Tarriela added.
China's coast guard said in a statement that Philippine ships "came dangerously close" and that its actions had been "in accordance with the law", without giving further details.
"On December 4, Philippine Coast Guard ships... attempted to intrude into China's territorial waters around Huangyan Island," coast guard spokesperson Liu Dejun said, using the Chinese name for Scarborough Shoal.
The Philippine ships "came dangerously close to regular law enforcement patrol vessels of the China Coast Guard", Liu said, without giving more information on the manoeuvres used by Beijing.
Scarborough Shoal -- a triangular chain of reefs and rocks -- has been a flashpoint between the countries since China seized it from the Philippines in 2012.
Since then, Beijing has deployed patrol boats that Manila says harass Philippine vessels and prevent Filipino fishermen from accessing a fish-rich lagoon there.
The shoal lies 240 kilometres (150 miles) west of the Philippines' main island of Luzon and nearly 900 kilometres from the nearest major Chinese land mass of Hainan.
