Two countries involved in a second incident this month at disputed Second Thomas Shoal.
The Philippine military said the Saturday morning confrontation lasted for nearly an hour and took place as it sought to resupply a small garrison of sailors on board the sunken Sierra Madre off Second Thomas Shoal.
The shoal, known as Ayungin in the Philippines, has been the site of multiple similar stand-offs in recent months. It lies about 200 kilometres (124 miles) from the western Philippine island of Palawan, and more than 1,000 kilometres (621 miles) from China’s southern Hainan island.
The military released a video clip showing a white ship marked China Coast Guard crossing the bow of a grey vessel it identified as the Philippine supply boat Unaizah May 4, and unleashing its water cannon.
“The UM4 supply boat sustained heavy damages at around 08:52 (00:52 GMT) due to the continued blasting of water cannons from the CCG vessels,” the military said in a statement, without going into detail about the damage.
A Philippine Coast Guard escort vessel later reached the damaged boat “to provide assistance”, the military said.
Gan Yu, a spokesman for the China Coast Guard, said that the Philippine convoy “forcibly intruded into the area despite the Chinese side’s repeated warnings and route controls”, adding the Chinese carried out “control, obstruction and eviction in accordance with law”.
China claims almost the entire South China Sea, despite an international court finding in 2016 that the nine-dash line on which it bases its claim was without merit. The Philippines claims areas of the sea around its coasts as do Brunei, Malaysia and Vietnam. The self-ruled island of Taiwan is also a claimant.
Manila has revived and expanded its military ties with the United States, a longtime ally, as the situation has become more tense.
The United States lays no claims to the strategic waters but has sent Navy ships on transit missions through the waterway in what it calls “freedom of navigation” operations, which have been criticised by China.
US Secretary of State Antony Blinken visited the Philippines last week and stressed the US commitment to Manila was “ironclad”.
Two days after that visit, the Chinese coastguard also tried to drive away Filipino scientists who landed on two cays near Scarborough Shoal, a contested South China Sea outcrop that Beijing seized from the Philippines after a months-long standoff in 2012.
The Unaizah May 4 had returned to sea after being damaged in a China Coast Guard water cannon attack off Second Thomas Shoal earlier this month, It was escorted by two Filipino coastguard vessels and two Philippine Navy ships, a Philippine military statement said.
Commodore Jay Tarriela, a Philippine Coast Guard spokesman for South China Sea issues, said in a separate statement that one of the escort vessels, the BRP Cabra, was “impeded and encircled” by three Chinese coastguard and other vessels early Saturday.
As a result, Cabra was “isolated from the resupply boat due to the irresponsible and provocative behaviour of the Chinese maritime forces”, he added.
The Chinese side showed a “disregard” for the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS), the statement said.
The Sierra Madre was run aground in 1999 and the troops living on the warship need frequent resupplies of food, water and other necessities.