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

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

The Chinese coast guard said in a statement on social media platform WeChat that the Philippine supply ship “ignored China’s repeated serious warnings – and unprofessionally approached a Chinese vessel dangerously in normal navigation, resulting in a collision.”

“The Philippines is solely responsible for this,” it said.

No comment was immediately available from the Philippine government.

The Philippines says the sea, located less than 200 nautical miles (370 kilometers) off its coast, falls within its internationally recognised exclusive economic zone and often cites a 2016 international arbitration ruling that invalidated China’s sweeping claims in the South China Sea on historical grounds.

There have been several incidents in recent months near the shoal, where the Philippines has maintained a checkpoint on the BRP Sierra Madre ship.

The territorial disputes have strained relations and raised fears the conflict could spark a military confrontation between China and the Philippines’ longtime treaty ally, the United States. Washington makes no territorial claim to the busy seaway, a major global trade route, but has warned it has an obligation to defend the Philippines if Filipino troops, ships and aircraft come under armed attack in the South China Sea.

Besides China and the Philippines, Vietnam, Malaysia, Brunei and Taiwan are also involved in long-running territorial disputes that are seen as a flashpoint in Asia and a delicate wedge in the long-running US-China rivalry in the region.