The Philippines condemned China's Coast Guard on Sunday for firing water cannon at its vessels in the disputed South China Sea, describing it as "illegal" and "dangerous".
China said it had taken "necessary controls" against Philippines boats that had "illegally" entered its waters.
Beijing claims almost all of the South China Sea, through which trillions of dollars in trade passes annually, and has ignored a 2016 international court ruling that its assertion has no legal basis.
The latest incident took place as the Philippine Coast Guard escorted boats carrying food, water, fuel and other supplies for Filipino military personnel stationed at Second Thomas Shoal in the Spratly Islands.
The US State Department condemned the Chinese actions, saying in a statement they were carried out by the coast guard and "maritime militia", and that they directly threatened regional peace and stability.
Second Thomas Shoal is about 200 kilometres (124 miles) from the Philippine island of Palawan and more than 1,000 kilometres from China's nearest major landmass of Hainan island.
China's coast guard and navy vessels routinely block or shadow Philippine ships patrolling the contested waters, Manila says.
Saturday's incident was the first time since November 2021 that the Chinese coast guard had used water cannon against a Philippine resupply mission to Second Thomas Shoal.
"The Philippine Coast Guard (PCG) strongly condemns the China Coast Guard's (CCG) dangerous maneuvers and illegal use of water cannons against the PCG vessels," the Philippine Coast Guard said in a statement.
"Such actions by the CCG not only disregarded the safety of the PCG crew and the supply boats but also violated international law."
The Armed Forces of the Philippines said China's coast guard had "blocked and water cannoned" one of its chartered resupply vessels.
Due to the "excessive and offensive" actions, a second chartered vessel was unable to unload its cargo for the routine troop rotation and resupply operation, military spokesman Colonel Medel Aguilar said in a statement.
"We call on the China Coast Guard and the Central Military Commission to act with prudence and be responsible in their actions to prevent miscalculations and accidents that will endanger people's lives," Aguilar said.
The British, Australian, and European Union embassies all expressed concern. The Japanese envoy in Manila called the incident "totally unacceptable", while the Canadian mission said it "unreservedly condemns the dangerous and provocative actions" of the Chinese Coast Guard.
China Coast Guard spokesman Gan Yu said in Beijing: "Two repair ships and two coast guard ships from the Philippines illegally broke into the waters... in China's Nansha Islands."
Beijing "implemented necessary controls in accordance with the law and stopped Philippine ships carrying illegal building materials", he said.
The Philippine foreign ministry said in response the Southeast Asian country "exercises sovereign rights" over the shoal, which is within its exclusive economic zone.
Latest maritime incident
Manila and Beijing have a long history of maritime disputes over the South China Sea, although former Philippine president Rodrigo Duterte was reluctant to criticize his more powerful neighbor as he sought closer ties with Beijing in the hope of attracting investment.
However, Philippine President Ferdinand Marcos has insisted since taking power in June 2022 he will not let China trample on his country's maritime rights and has gravitated towards the United States as he seeks to strengthen defense ties.
Tensions between Manila and Beijing flared this year after a Chinese Coast Guard vessel allegedly used a military-grade laser against a Philippine Coast Guard boat near Second Thomas Shoal.
Beijing accused the Philippine boat of intruding into China's sovereign waters without permission.
After China occupied Mischief Reef in the mid-1990s, the Philippines ran a derelict navy vessel aground on the nearby shoal to assert Manila's territorial claims in the waters.
Members of the Philippine Marines are based there.
In another incident in April, a Chinese Coast Guard ship cut off the Philippine patrol vessel Malapascua as it carried journalists near Second Thomas Shoal.