China said it had taken "necessary controls" against Philippine boats.
The Philippines has condemned the China Coast Guard (CCG) for firing water cannon at its vessels in the disputed South China Sea. The boats were going to Ayungin Shoal on Saturday for a resupply mission at the BRP Sierra Madre.
The Philippine Coast Guard (PCG) issued a statement criticising the China Coast Guard's "dangerous manoeuvres and illegal use of water cannons" against its vessels escorting the indigenous boats chartered by the Armed Forces of the Philippines (AFP) to deliver food, water, fuel, and other supplies to military troops stationed on BRP Sierra Madre at Second Thomas Shoal."
"The PCG calls on the China Coast Guard to restrain its forces, respect the sovereign rights of the Philippines in its exclusive economic zone and continental shelf, refrain from hampering freedom of navigation, and take appropriate actions against the individuals involved in this unlawful incident," PCG spokesperson for the West Philippine Sea Commodore Jay Tarriela said.
The US State Department condemned the Chinese actions, saying in a statement that 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, Hainan Island.
China's coast guard and navy vessels routinely block or shadow Philippine ships patrolling the contested waters, Manila said.
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.
"Such actions by the CCG not only disregarded the safety of the PCG crew and the supply boats but also violated international law, including the 1982 United Nations Convention on the Law of the Sea (UNCLOS), the 1972 Convention on the International Regulations for Preventing Collisions at Sea (COLREGS), and the 2016 Arbitral Award," the PCG stated.
It further called on the CCG to restrain its forces, respect the Philippines' sovereign rights, and observe international maritime obligations.
"We ask that the China Coast Guard, as an organisation with a responsibility to observe state obligations under UNCLOS, COLREGs, and other relevant instruments of international maritime safety and security, to cease all illegal activities within the maritime zones of the Philippines," the PCG further stated.
(With inputs from agencies)