China’s coast guard said on Tuesday (Apr 30) it barred a Philippine coast guard ship and another vessel from waters adjacent to the Scarborough Shoal, reported the Chinese state media.

Tensions flared again in the South China Sea as the Philippine coast guard offered no further details on a recent incident near the Scarborough Shoal. This submerged reef is a flashpoint between the two nations.

The Philippines considers it within its exclusive economic zone, an area where it has special rights regarding resources. However, China also claims the shoal.

Both countries have accused each other of aggressive actions in the area in recent months. The Philippines even summoned a Chinese diplomat to express their disapproval.

China and Philippines previously said they would seek better communications and management around skirmishes in the vast South China Sea, but tensions have increased recently, especially after Philippines forged stronger diplomatic and military ties with the United States.

China claims almost the entire South China Sea, a conduit for more than $3 trillion of annual ship-borne commerce, including parts claimed by the Philippines, Vietnam, Indonesia, Malaysia and Brunei. The Permanent Court of Arbitration in 2016 said China’s claims had no legal basis.

(With inputs from agencies)