The Philippines on Friday denounced China's alleged assault of Vietnamese fishermen in the South China Sea, where Manila and Beijing are also locked in violent confrontations that have led to fears of armed conflict.

Vietnam has accused "Chinese law enforcement forces" of beating the 10 fishermen with iron bars and robbing them of thousands of dollars' worth of fish and equipment on Sunday off the Paracel Islands.

A Chinese foreign ministry spokesperson acknowledged an incident took place there, but disputed the Vietnamese version of the events.

China and Vietnam both claim the Paracel Islands, but the Philippines does not. 

"We strongly condemn the violent and illegal actions of Chinese maritime authorities against Vietnamese fishermen near the Paracel Islands on September 29, 2024," Philippine National Security Adviser Eduardo Ano said in a statement.

He described the "unjustified assault" as an "alarming act with no place in international relations".

The Philippine foreign department also issued a statement Friday saying it was aware of the "serious incident".

"The Philippines has consistently denounced the use of force, aggression and intimidation in the South China Sea, and emphasised the need for actors to exercise genuine self-restraint," it said.

"It is a paramount obligation to ensure the safety at sea of vessels and their crew, especially fisherfolk."

The incident came just over three months after Chinese law enforcement personnel armed with knives, sticks and an axe attacked Filipino troops attempting to resupply a Philippine garrison on Second Thomas Shoal in the Spratly archipelago.

The Chinese seized guns and other equipment and damaged Philippine boats, while a Filipino sailor lost a thumb in the June 17 melee.

Chinese coast guard and other vessels have in recent months also rammed, water-cannoned and blocked Philippine government vessels on several occasions around Second Thomas Shoal and Sabina Shoal in the Spratlys, as well as Scarborough Shoal in another area of the sea.

Beijing claims most of the South China Sea and has for years sought to expand its presence in contested areas there, brushing aside an international ruling that its claim to most of the waterway has no legal basis.

It has built artificial islands armed with missile systems and runways for fighter jets, and deployed vessels that the Philippines says harass its ships and block its fishers.