China has expressed grave concern about the Philippines’ recent activities in the West Philippine Sea after President Ferdinand Marcos Jr. described Beijing’s actions in the area as “worrisome.”

In a press briefing on Wednesday night (Philippine time), China Foreign Ministry spokesperson Mao Ning also reiterated Beijing’s sovereign rights over the WPS.

“China’s position on the South China Sea is consistent and clear,” Mao said when asked to comment on Marcos's description of Beijing’s actions in the WPS.

“We express grave concern over the Philippines’ recent activities in the South China Sea that infringe on China’s sovereignty and will continue to take necessary measures to firmly safeguard our territorial sovereignty and maritime rights and interests, and keep the South China Sea peaceful and stable,” she added.

Marcos, before leaving for his two-day state visit to Australia, aired his thoughts on the supposed assertiveness of China in the WPS.

“It’s really worrisome. Before, it’s just the China Coast Guard that’s making moves in our area. Now their Navy and fishing boats are joining them, so the situation is really changing,” Mr. Marcos said.

Over the weekend, the Philippine Coast Guard accused its Chinese counterpart of jamming the signal of Filipino vessels’ tracking systems in the WPS.

The Philippine Navy, for its part, confirmed the report that it has monitored “interference” in its electronic capabilities in the WPS.

It, however, did not specifically identify the source of interference.

China claims the vast South China Sea, including the West Philippine Sea, which is within the Philippines’ 200-nautical mile exclusive economic zone.

In 2016, the Permanent Court of Arbitration rejected Beijing’s historical claims in the West Philippine Sea and favored Manila’s sovereign rights in the area.

Despite this, the 2016 Arbitral Award on the South China Sea remains on paper as China has continued to reject the ruling and assert its claim in the area.