The trio, who worked for the Philippine Department of Defense, Navy and Coast Guard, provided their Chinese handlers with lists of military personnel and other sensitive information, National Security Council (NSC) spokesman Cornelio Valencia told AFP.

Operational details about resupply missions in the contested South China Sea, where China and the Philippines have frequently clashed in recent years, were also included in the information handed over, he said.

"There was co-optation over a period of time," Valencia said of efforts to woo the defence personnel, who he described as low-level analysts.

"At the start you are not aware. And then you're surprised they're already asking you for sensitive data."

"At the end of the day, it's always money," he said of their motives.

Valencia said the three, whose names and genders he did not disclose, were now actively cooperating with the government "to ensure we no longer have a problem".

In a statement released Wednesday night, the NSC said it had "addressed and terminated" operations taken at "the behest of Chinese intelligence", without offering details of the alleged espionage.

"For reasons of national security, we cannot discuss identities, methods, or timelines so as not to jeopardize ongoing operations," the security agency said.

"Nonetheless, necessary actions have been taken against the individuals concerned -- all Filipino nationals -- who have all confessed their complicity in espionage activities and are cooperating with authorities."

The Chinese embassy in Manila did not immediately respond to requests for comment.

Wednesday's NSC statement cited a recent investigation in local outlet Rappler, which first reported that Chinese handlers had sought information about maritime deployments and resupply missions in the South China Sea.

The Philippines last year announced multiple arrests of Chinese nationals over alleged espionage.

In April, a Chinese man was apprehended while operating a surveillance device near the offices of the Philippine election commission, authorities said, less than two weeks before the country's mid-term elections.

The man was allegedly using an "IMSI catcher", a device capable of mimicking a cell tower and snatching messages from the air in a one-to-three-kilometre (about 3,200-to-9,800-feet) radius.

Two Chinese men detained in February 2025 were accused of using the same device while driving near sensitive government and military locations in Manila.