The incident occurred near the contested Scarborough Shoal as the Philippine Coast Guard escorted boats distributing aid to fishermen in the area, spokesman Commodore Jay Tarriela said in a statement.

Video released by Manila showed a China Coast Guard ship and a much larger vessel bearing the number 164 on its hull colliding with a loud crash.

Additional footage and photos released later by the Philippine Coast Guard showed the stricken Chinese vessel still afloat but with its entire bow crumpled inward.

"The (China Coast Guard vessel) CCG 3104, which was chasing the (Filipino coast guard vessel) BRP Suluan at high speed, performed a risky manoeuvre from the (Philippine) vessel's starboard quarter, leading to the impact with the PLA (People's Liberation Army) Navy warship," Tarriella said in a statement.

"This resulted in substantial damage to the CCG vessel's forecastle, rendering it unseaworthy."

At a later press briefing, Tarriella said that crew members aboard the smaller Chinese vessel had been visible in its front section just before the collision.

"We're not sure whether they were able to rescue those personnel who were in front prior to the collision. But we are hoping that these personnel are in good condition," he told reporters.

Tarriela said the Chinese crew "never responded" to the Philippine ship's offer of assistance.

Gan Yu, a Chinese coast guard spokesperson, confirmed that a confrontation had taken place without mentioning the collision.

"The China Coast Guard took necessary measures in accordance with the law, including monitoring, pressing from the outside, blocking and controlling the Philippine vessels to drive them away," he said in a statement.

China's Ministry of Foreign Affairs did not confirm or deny the collision when asked about it by AFP.

Monday's incident is the latest in a series of confrontations between China and the Philippines in the South China Sea, which Beijing claims almost entirely despite an international ruling that the assertion has no legal basis.

More than 60 percent of global maritime trade passes through the disputed waterway.

Speaking at a morning news conference, Philippine President Ferdinand Marcos said the country's patrol vessels would "continue to be present" in the area to defend, as well as exercise Manila's sovereign rights over, what it considers to be part of its territory.

The 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.

Earlier in the confrontation, the BRP Suluan was "targeted with a water cannon" by the Chinese but "successfully" evaded it, Tarriela's statement said.

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