The swarming of Chinese fishing vessels in several locations of the country's exclusive economic zone in the West Philippines Sea has alarmed the government forces.

The Western Command of the Armed Forces of the Philippines on Thursday reported the "concerning resurgence" of a total of 30 Chinese fishing vessels in the WPS, based on its aerial patrols conducted from 6 to 7 September.

Some 23 vessels were monitored in Rozul (Iroquois) Reef. There were five ships in Escoda (Sabina) Shoal and two in Baragatan (Nares) Bank.

The Philippine Navy, likewise, spotted 33 Chinese fishing vessels in Rozul Reef during a routine air patrol on 24 August, which was followed by reports of massive coral harvesting.

The WesCom said the same patrol also monitored swarming activity on Escoda Shoal. This area serves as a "marker for the approach to Ayungin (Second Thomas) Shoal" and where "unauthorized Chinese shadowing of Philippine watercraft typically occurs."

The military unified command stressed that Rozul Reef is located within the Philippine EEZ and continental shelf, "making this intrusion a violation of Philippine sovereign rights and jurisdiction."

Also, 48 Chinese fishing boats were seen last 30 June in Iroquois Reef, located south of the oil and gas-rich Recto Bank—which lies within the country's EEZ.

"The increased presence of CFVs raises concerns regarding the potential implications for Philippines' maritime security, fisheries conservation, territorial integrity, and preservation of the marine environment," WesCom lamented.

It said such activities have been a "source of tension in the WPS and have contributed to instability in the region."

"As the Chinese swarming activity resurges, the Philippines continues to remain vigilant and take necessary measures to safeguard its vital national interests and maintain stability in the region," it added.