The National Bureau of Investigation arrested a Chinese man and two Filipinos for espionage activities that targeted not only military sites in the country but also power installations — and even the Malampaya offshore gas plant.

The three suspects, Deng Yuanqing, Ronel Jojo Balundo Besa and Jason Amado Fernandez, were accused of engaging in intelligence, surveillance and espionage operations “prejudicial to our national security,” NBI Cybercrimes Division chief Jeremy Lotok said in a briefing on Monday, which was also attended by Armed Forces of the Philippines Chief of Staff Gen. Romeo Brown Jr.

The suspects are charged with espionage and violation of Republic Act No. 10175 of 2012, or the Cybercrimes Prevention Act.

Their case stemmed from a report by AFP Marine Activists alleging that a group of Chinese nationals were engaged in surveillance activities that threatened the country’s national security under the guise of developing autonomous vehicles.

Acting on that report, the NBI identified six members of the group of activists, including Deng, a software engineer and financier from China.

Lotok described Deng as a graduate of the People’s Liberation Army University of Science and Technology in Nanjing and an expert in control and automation engineering.

Deng was also suspected of being a mole or “sleeper agent” who had been in the country for five years.

His activities appeared “completely normal” and he was able to blend in with various groups “without drawing attention to himself,” the NBI said.

Besa and Fernandez served as Deng’s drivers and aides, reportedly visiting military and police headquarters, municipal halls and other local government offices, and even power installations.

The areas they visited included a substation of the National Grid Corporation of the Philippines in Batangas province and even the headquarters of the Philippine Army’s 201st Infantry Brigade in Laguna, Cavite, the NBI said.

Deng and company also visited the Malampaya gas field off the coast of Palawan, the NBI said.

Lotoc said their operation only began last December.

Browner, for his part, said, “We saw that some of the [targeted] areas were EDCA sites.” He was referring to the nine sites in the country selected for the Enhanced Defense Cooperation Agreement (EDCA) between the Philippine and US armed forces.

In “military targeting,” the AFP chief said information such as activities in the area and vehicles that may be moving through these areas is very important.

“There is information that cannot be captured by satellites but can be observed on the ground. “These are all very important pieces of information, and if used by the military, we believe they would be very dangerous for us, especially since we have seen that some of the areas they visited, as I mentioned, are EDCA sites and include military bases. This is very dangerous when the data is used by another military,” Browner said.

The suspects have finished mapping the entire Luzon and were planning to survey the rest of the archipelago before they are arrested, Lotoc said.