Beijing and Manila traded blame on Sunday for two collisions between Chinese vessels and Philippine boats on a resupply mission to Filipino troops on a remote outpost in the disputed South China Sea.

The incidents happened near Second Thomas Shoal in the Spratly Islands, a hotly contested region where Beijing deploys ships to assert its claims over almost the entire sea.

A Philippine government task force said the “dangerous blocking manoeuvers of China Coast Guard vessel 5203 caused it to collide with the Armed Forces of the Philippines-contracted indigenous resupply boat” about 25 kilometres (15 miles) from Second Thomas Shoal.

China said the “slight collision” happened after the resupply boat ignored “multiple warnings and deliberately passed through law enforcement in an unprofessional and dangerous manner”, state broadcaster CCTV reported, citing the foreign ministry.

In another incident, a Philippine coastguard vessel escorting the routine resupply mission was “bumped” by what the Philippine task force described as a “Chinese Maritime Militia vessel”.

China, however, accused the Philippine boat of “deliberately” stirring up trouble by reversing in a “premeditated manner” into a Chinese fishing vessel.

A video released by the Philippine military showed the bow of the Chinese coastguard ship and the stern of the resupply vessel briefly touching.

The Philippine vessel continues on its course. It is not clear if there was any damage.

A second resupply boat was able to reach the grounded BRP Sierra Madre and “successfully resupply our troops and personnel stationed there”, the statement said.

“The National Task Force for the West Philippine Sea condemns in the strongest degree the latest dangerous, irresponsible, and illegal actions of the CCG and the Chinese Maritime Militia done this morning,” the task force said in a statement.

It said the “provocative, irresponsible, and illegal action” of the Chinese coastguard boat had endangered the safety of the crew on the supply boat.

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

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

China said “responsibility lies entirely with the Philippines” for Sunday’s incidents.

As China moves ever more confidently to assert its claims to sovereignty over the waters, officials and experts have warned of the potential for collisions.

“This is exactly the kind of event that can happen given their dangerous manoeuvring,” said Jay Batongbacal, director of the University of the Philippines’ Institute for Maritime Affairs and Law of the Sea.

Batongbacal said the Chinese coastguard had deliberately hit the Philippine resupply vessel to see how Manila would respond and test the resolve of the Philippines’ longtime ally Washington.

“You don’t accidentally hit another vessel out in the open ocean,” Batongbacal told AFP.

US condemns ‘latest disruption’

The Philippine Navy deliberately grounded the World War II-era BRP Sierra Madre on the Second Thomas Shoal in 1999 to check China’s advance in the waters.

The troops stationed on the crumbling ship depend on regular supply deliveries for their survival.

The Philippines has outposts on nine reefs and islands in the Spratlys, including Second Thomas Shoal.

US Ambassador to the Philippines MaryKay Carlson said the United States condemned China’s “latest disruption of a legal Philippine resupply mission” that put “the lives of Filipino service members at risk”.

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 cannons against a Philippine resupply mission to Second Thomas Shoal, preventing one of the boats from delivering its cargo.

A Chinese ship in April narrowly missed colliding with a much smaller Philippine Coast Guard vessel in the same area.