China warned the Philippines on Monday to behave cautiously and seek dialogue, saying their relations were at a "crossroads" as new confrontations between their coastguards over maritime claims deepened tensions.

Philippines resupply mission in the South China Sea.

It was the second such warning by the Chinese foreign ministry in three months as the two countries openly sparred over territorial claims in the Spratly Islands, a mostly uninhabited archipelago in the South China Sea.

The message was delivered by Chinese Vice Foreign Minister Chen Xiaodong during a phone call with Philippine counterpart Theresa Lazaro amid worsening friction over altercations at the Second Thomas Shoal in the South China Sea.

In the call, Lazaro relayed Manila's "strongest protest against the aggressive actions" by the China Coast Guard and maritime militia against a Philippines' resupply mission in the South China Sea, her ministry said in a statement.

Chen said in a statement: "China once again urges the Philippines to honour its commitments and consensus, stop its maritime abuses and provocations, stop any unilateral actions that may complicate the situation, and earnestly return to the right track of properly handling differences through dialogue and consultation with China."

The Philippines accused China's coastguard of using water cannon against a civilian boat supplying troops on Saturday at the Second Thomas Shoal, which it said had damaged the boat and injured some crew.

It was the latest in a series of flare-ups in the past year.

The Philippines foreign ministry summoned China's charge d'affaires in Manila on Monday to protest at "aggressive actions" in the wake of the incident.

"China's continued interference with the Philippines' routine and lawful activities in its own exclusive economic zone (EEZ) is unacceptable," it said in a separate statement, adding that a diplomatic protest had been lodged in Beijing.

"It infringes upon the Philippines' sovereign rights and jurisdiction," it said, demanding Chinese vessels quit the area.

China's coastguard said on Saturday it had taken necessary measures against Philippine vessels intruding in its waters.

Beijing claims almost the entire South China Sea as its own, including the Second Thomas Shoal, which is within the Philippines' 200-mile (320-km) EEZ.

The Philippines intentionally grounded an old warship at the shoal in 1999 as a means of bolstering its territorial claims and has kept a small contingent of military there ever since.

China's foreign ministry said on Monday the Philippines had reneged on a promise to tow away the ship, "violating the commitments it has made to the Chinese side on many occasions".

The Philippines has repeatedly denied making any such commitment and said it will not abandon its position at the Second Thomas Shoal.

China has deployed hundreds of coastguard vessels throughout the South China Sea to patrol what it deems its waters, despite a 2016 Permanent Court of Arbitration ruling in a case brought by Manila that said the claim had no basis under international law. China has refused to recognise that outcome.

Philippine security chiefs convened a high-level meeting on Monday over the reported water cannon incident to prepare recommendations to put to President Ferdinand Marcos Jr on ways forward in the dispute.

CHINA SUSPICIOUS OF US-PHILIPPINES ENGAGEMENT

Since taking power in 2022, Marcos has adopted a tough line against what he sees as Chinese hostility and rejected Chinese pressure to steer clear of maritime features it claims.

China views with suspicion efforts by Marcos to deepen engagement with defence treaty ally the United States, including increasing base access for U.S. troops and expanding military exercises to include joint air and sea patrols.

Washington has said it stands with the Philippines as it condemned the "dangerous actions" of China. Japan, the United Kingdom, Germany, France, Canada and Australia have also issued statements of support for the Philippines.

"The U.S. is not a party to the South China Sea issue but repeatedly intervened, provoked the maritime issues between China and the Philippines," Chinese foreign ministry spokesperson Lin Jian told a press conference on Monday.

Philippine Defence Secretary Gilberto Teodoro suggested on Monday that China should prove the strength of its maritime claims through arbitration, rather than ambiguity.

"If China is not afraid to state its claims to the world, then why don't we arbitrate under international law?" Philippines' Teodoro told reporters. "No country believes (their claims) and they see this as their way to use force, intimidate and bend the Philippines to their ambitions."

Philippines says Chinese envoy summoned over 'aggressive actions' off reef

Aerial video footage shows a China Coast Guard ship (2nd L) and vessels identified by the Philippine Coast Guard as 'Chinese maritime militia' (L and R) surrounding the Philippine ship BRP Cabra.

The Philippines said Monday it had summoned a Chinese envoy over "aggressive actions" by the China Coast Guard and other vessels near a reef off the Southeast Asian country's coast, while Beijing lodged its own complaint.

Deputy foreign ministers from the two countries later held a phone call in which China urged Manila to "pull back from the brink" and stop "provoking trouble at sea", Beijing said.

Beijing and Manila have a long history of maritime territorial disputes in the South China Sea and there have been repeated confrontations between their vessels near disputed reefs in recent months.

The latest incident took place Saturday near Second Thomas Shoal in the Spratly Islands during a regular Philippine mission to resupply Filipino troops garrisoned on the BRP Sierra Madre, a grounded navy ship.

The Philippines said the China Coast Guard blocked its supply vessel and damaged it with water cannon, injuring three soldiers.

The China Coast Guard has defended its actions, describing them as "lawful regulation, interception and expulsion" of a foreign vessel that "tried to forcefully intrude" into Chinese waters.

Manila conveyed its "strong protest against the aggressive actions undertaken by the China Coast Guard and Chinese Maritime Militia against the rotation and resupply mission undertaken by the Philippines in Ayungin Shoal," the Department of Foreign Affairs said on Monday, using the Filipino name for Second Thomas Shoal.

It said the Philippine embassy in Beijing also lodged a similar protest with the Chinese foreign ministry.

"In these demarches, the Philippines stressed, among others, that China has no right to be in Ayungin Shoal," the foreign affairs department said.

"The Philippines demands that Chinese vessels leave the vicinity of Ayungin Shoal and the Philippine exclusive economic zone immediately."

On Monday, China's embassy in the Philippines said it had complained to Manila over what it called the "illegal intrusion" of the Southeast Asian country's ships into its waters.

In the later phone call, Chinese vice foreign minister Chen Xiaodong said bilateral relations were "currently at a crossroads".

The Philippines must "pay serious attention to China's concerns, pull back from the brink, and return as soon as possible to the correct track of resolving differences with China through negotiation and consultation," Chen said.

Second Thomas Shoal is about 200 kilometres (120 miles) from the western Philippine island of Palawan, and more than 1,000 kilometres from China's nearest major landmass, Hainan island.

It is the same location where there have been recent collisions between vessels belonging to both countries, as well as water cannoning by the China Coast Guard.

- Cooling diplomatic relations -

China claims almost the entire South China Sea, brushing off rival claims from other countries including the Philippines and an international ruling that its assertion has no legal basis.

The United States, which has a mutual defence pact with Manila, has denounced the attack.

It came days after visiting US Secretary of State Antony Blinken said the United States stood by its "ironclad" commitments to defend longtime ally the Philippines against armed attack in the South China Sea.

Philippine Defence Secretary Gilbert Teodoro on Monday challenged Beijing to seek arbitration, which he said was the "best way of solving a legal dispute sustainably".

"That's why they don't like that," Teodoro told reporters.

Relations between Manila and Beijing have cooled under Philippine President Ferdinand Marcos as he seeks to deepen cooperation with the United States and regional neighbours, while standing up to Chinese aggression towards Philippine vessels.

Chinese and Philippine officials agreed in January on the need for closer dialogue to deal with "maritime emergencies" in the South China Sea, including Second Thomas Shoal.

But Manila said Monday that China's "aggressive actions call into question its sincerity in lowering the tensions and promoting peace and stability in the South China Sea."

Despite the attack, Philippine officials said the damaged vessel and a coast guard escort ship that came to its aid later deployed rigid-hull inflatable boats to deliver its cargo and personnel to the Filipino outpost.

Filipino soldiers stationed on the shoal live on the crumbling BRP Sierra Madre and require frequent resupplies for food, water and other necessities as well as transport for personnel rotations.

Apart from supplies and equipment, the Philippine military said six navy personnel were delivered to the BRP Sierra Madre on Saturday, replacing one soldier who was recently evacuated on medical grounds.

The damaged supply boat and its escorts sailed back to port after completing their mission, the task force said.

China vows to safeguard its territorial integrity after South China Sea incident

China's defence ministry warned the Philippines against "provocative" actions and said China would safeguard its territorial sovereignty on Sunday, a day after an incident in disputed waters of the South China Sea.

"We warn the Philippines to stop making any remarks that may lead to the intensification of conflicts and escalation of the situation, and stop all infringing and provocative actions," the defence ministry said in a statement.

"If the Philippines repeatedly challenges China's bottom line, China will continue to take firm and decisive measures to firmly safeguard its territorial sovereignty and maritime rights and interests," the statement continued.

The remarks came after China's coast guard said had it taken measures against Philippine vessels in disputed waters near the Second Thomas Shoal and Spratly Islands a day before, actions that the Philippines had called "irresponsible and provocative".

The incident included the use of water cannons against a civilian boat hired to resupply troops, the Philippine task force on the South China Sea said in a statement on Saturday.