China may have committed a "potential breach" when it sent a ship to navigate around the Benham Rise for around three months, National Security Adviser Hermogenes Esperon Jr. said Wednesday.
"They (Chinese) stayed for several months... Three months of lingering in the area is not simply innocent passage or freedom of navigation," Esperon told members of the Senate Committees on Economic Affairs, and Finance.
He added: "There is a potential breach [of national security] but it being a research ship which did not conduct any soundings or researches on the seabed, I would not put it in the security fence but rather on the economic side of things."
A drone was also seen hovering over the Benham Rise earlier this month, defense officials said.
"It could have been launched from a nearby area...They could be taking pictures," Esperon told senators.
Countries that wish to conduct researches in the 24 million-hectare continental shelf must first engage in a "government-to-government" dialogue and secure "consent" from the Philippines, Esperon said.
President Rodrigo Duterte earlier said that he allowed China to ply by the area, but the Palace kept mum on the details of the agreement.
Heads of the Departments of National Defense, and Foreign Affairs denied being informed about the said deal between Duterte and the Chinese government.
China earlier said that it does not question the Philippines' rights to the Benham Rise, but did not specify the activities undertaken by the Chinese vessel that was deployed to the area.
Esperon said the government must beef up its research and surveillance capabilities to monitor all activities within the country's exclusive economic zones (EEZ).
"We are one country that has a big EEZ but...no satellites for imagery... We need to have a better view to have a better management of our resources," he said.