China's coast guard said it had warned and followed Philippine vessels on Friday near the Second Thomas Shoal in the South China Sea that were carrying out a resupply mission to a grounded warship on the atoll.
Disputes over the grounded World War Two-era warship Sierra Madre have heated up after China sprayed a Philippine vessel with a water cannon on an Aug. 5 resupply mission, with Philippines rejecting Beijing's repeated calls to tow away the ship.
Two Philippine supply boats and two coast guard ships entered the waters adjacent to the shoal without the permission of the Chinese government, the coast guard said.
The Second Thomas Shoal, known in China as Renai Reef, and Ayungin in Manila, lies within the Philippines' exclusive economic zone and is home to a handful of troops living aboard the warship, grounded there in 1999 to reinforce its sovereignty claim.
China's coast guard said it issued a stern warning to the Philippine vessels and followed them throughout the journey, repeating China's "firm" opposition to the Philippines' transportation of "illegal" construction materials to the grounded warship.
Relations between the two countries froze over the South China Sea under Philippine President Ferdinand Marcos Jr., with Manila pivoting back to the United States, which supports the Southeast Asian nation in its maritime disputes with China.
Reuters had reported that Manila is in talks to develop a civilian port in the remote northernmost islands of the Philippines, which is less than 200 km (125 miles) from Taiwan.
The Southeast Asian nation also upgraded bilateral ties with Australia to a strategic partnership amid rising security challenges, including China's stronger presence in the South China Sea.
