A Chinese vessel and a Philippine supply ship collided near the disputed Spratly Islands in the South China Sea on Monday, China’s coast guard said.

The coast guard said the Philippines ship entered waters near the Second Thomas Shoal, a submerged reef in the Spratly Islands that is part of territory claimed by several nations.

The Chinese coast guard said in a statement on the social media platform WeChat the ship “ignored China’s repeated solemn warnings… and dangerously approached a Chinese vessel in normal navigation in an unprofessional manner, resulting in a collision”.

“The Philippines is entirely responsible for this,” it added.

The Philippines says the area, which lies less than 200 nautical miles from its coast, falls within its internationally recognised exclusive economic zone and often cites a 2016 international arbitration ruling that invalidated China’s expansive claims in the South China Sea based on historical grounds.

Several incidents have happened in recent months near the disputed area, where the Philippines maintains a post aboard the BRP Sierra Madre ship.

The territorial disputes have strained relations and sparked fears the conflict could bring China and the United States, a long-time treaty ally of the Philippines, into a military confrontation.

Washington lays no territorial claims to the busy seaway, a key global trade route, but has warned it is obligated to defend the Philippines if the country’s forces, ships and aircraft come under an armed attack in the South China Sea.

Aside from China and the Philippines, Vietnam, Malaysia, Brunei and Taiwan are also involved in the long-seething territorial disputes, which are regarded as a flashpoint in Asia and a delicate fault line in the long=standing US-China rivalry in the region.