Manila said Monday that Chinese vessels "intentionally hit" Philippine boats at the weekend, escalating a diplomatic row over two collisions in the South China Sea.

The countries have traded blame over Sunday's incidents near Second Thomas Shoal in the Spratly Islands, with both sides filing diplomatic protests and releasing videos to support their accusations.

The two collisions happened during a Philippine resupply mission to troops stationed on a navy vessel that was grounded on the shoal in 1999 to assert Manila's territorial claims.

Philippine officials accused a Chinese coastguard ship and a "militia" vessel of "dangerous maneuvering" that resulted in collisions with a Philippine resupply boat and a Philippine Coast Guard vessel.

Philippine Defense Secretary Gilbert Teodoro took it one step further Monday, labelling the Chinese actions near Second Thomas Shoal deliberate.

"Chinese coast guard and maritime militia vessels, in blatant violation of international law, harassed and intentionally hit Unaiza May 2 and Philippine Coast Guard vessel BRP Cabra," Teodoro said.

"We are here to really decry in the strongest possible terms this egregious violation and illegal act within the (Philippines') 200 nautical mile exclusive economic zone and the obfuscation of the truth by China's distorting the story to fit its own ends."

His comments came hours after Philippine President Ferdinand Marcos met with security officials and ordered the coastguard to investigate the incident, which was "being taken seriously at the highest level of government", his communications team said.

Chinese foreign ministry spokesman Mao Ning on Monday accused the Philippines of "continuing to spread false information and hype things up".

Earlier Monday, the Philippine foreign ministry summoned China's ambassador to Manila and lodged a diplomatic protest over the incident.

Spokeswoman Teresita Daza said the ambassador was unavailable and was represented by his deputy chief of mission.

"Ayungin Shoal is part of our exclusive economic zone and continental shelf and we have sovereign rights and jurisdiction over it," Daza said, using the Philippine name for the shoal.

The Chinese foreign ministry and embassy in Manila also issued "stern representations to the Philippines" over its "infringements" at Ren'ai Reef, Mao said, using China's name for Second Thomas Shoal.

China has said a "slight collision" happened after the Philippine resupply boat ignored "multiple warnings and deliberately passed through law enforcement in an unprofessional and dangerous manner".

In the other incident, China accused the Philippine Coast Guard of reversing in a "premeditated manner" into a Chinese fishing vessel.

No Filipino crew member was injured, but the supply boat was damaged and forced to turn back, Philippine officials said.

A second supply boat reached the tiny garrison on the grounded BRP Sierra Madre and unloaded its cargo.

Manila's longtime ally Washington has led a chorus of international criticism of China's alleged interference in the resupply mission.

The US State Department on Sunday reiterated its mutual defence pact with the Philippines "extends to armed attacks on Philippine armed forces, public vessels, and aircraft –- including those of its Coast Guard –- anywhere in the South China Sea".

'Arbitral ruling is binding'

China claims almost the entire South China Sea, through which trillions of dollars in trade passes annually, and has ignored a 2016 international ruling that its assertion has no legal basis.

Second Thomas Shoal is about 200 kilometers (124 miles) from the western Philippine island of Palawan, and more than 1,000 kilometers from China's nearest major landmass, Hainan island.

Previously warm ties between Manila and Beijing have cooled since Marcos took power in June 2022, as he seeks stronger relations with the United States.

The Marcos administration has publicly criticized Chinese actions in the South China Sea, publishing photos and videos to support its claims of Chinese harassment and the blocking of its vessels.

Beijing has released its own images of the incidents.

Despite the challenges, the Philippines would "continue to do what is necessary" to supply its troops on the BRP Sierra Madre with provisions, said Jonathan Malaya, assistant director general of the National Security Council.

Manila and Beijing have a long history of maritime disputes in the South China Sea.

Tensions flared in August when China Coast Guard vessels used water cannon against a Philippine resupply mission to Second Thomas Shoal, preventing one of the boats from delivering its cargo.