China and the Philippines are accusing each other of ramming their ships in the South China Sea.
China fired a water cannon and rammed resupply vessels, the Philippine Coast Guard said.
Video from the Philippine Coast Guard shows a Chinese Coast Guard vessel firing the cannon at a much smaller Philippine patrol vessel.
But China’s coast guard said the Philippine vessel intentionally rammed its ship, too.
China’s use of water cannon amounts to “illegal and aggressive actions”, according to the Philippines.
Beijing said it was using legitimate “control measures”.
The confrontation happened near Second Thomas Shoal, a submerged reef west of the Philippines and south of Hong Kong.
The territory, which is disputed and claimed by several nations, is occupied by the Philippines Navy after a ship was intentionally grounded there in 1999.
The shoal is part of what are known internationally as the Spratly Islands.
Beijing and Manila have been playing cat-and-mouse around the uninhabited reef as the Philippines sends resupply missions to Filipino soldiers living aboard the ageing warship that was deliberately run aground.
China claims almost the entire South China Sea – which it sees as a vital link for more than $3trn (£2.4trn) of annual ship-borne commerce.
Parts of the sea are also claimed by the Philippines, Vietnam, Indonesia, Malaysia and Brunei.
In 2016, the Permanent Court of Arbitration said China’s claims had no legal basis.
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In a statement, China’s coast guard said two Philippine vessels had ignored repeated warnings and had “illegally entered the waters adjacent to Ren’ai Reef in the Nansha Islands without the approval of the Chinese government”.
It added that the Unaizah Mae 1 “made an unprofessional and dangerous sudden turn, intentionally ramming into China Coast Guard vessel 21556”.
It claimed the Philippine side bore full responsibility.
But Philippine Coast Guard spokesperson Jay Tarriela said on X, formerly known as Twitter, that the “M/L Kalayaan suffered serious engine damage”, adding: “Contrary to China Coast Guard disinformation, UM1 rammed by CCG vessel.”
The US’s ambassador to Manila, MaryKay Carlson, said on X that China’s “aggression undermines regional stability in defiance of a free and open Indo-Pacific”.