Watch more in iWantv or TFC.tv

MANILA - A former national security adviser on Tuesday said he is puzzled why the Philippine government would allow China to conduct scientific research off the Pacific coast.

The Department of Foreign Affairs granted the request of a Chinese entity to do research in waters where the Benham Rise is located, according to Representative Gary Alejano. It was later disclosed that President Rodrigo Duterte made the call to allow the survey.

• Roque: Duterte made call on China's Benham Rise research

"I’m just a little puzzled why we would allow an entity that already grabbed a big chunk of our exclusive economic zone an entry to Benham Rise," Roilo Golez told ANC's Headstart.

Golez noted China may be "lusting" after the natural resources in Benham Rise, which is supposedly rich in fish and methane gas hydrates.

"I’m very worried that China may be lusting for the resources available there plus the geostrategic value...The Constitution is very clear that the state must protect our marine wealth in our exclusive economic zone, territorial sea, etc., and reserve its use exclusively for Filipino citizens," he said.

Benham Rise, renamed Philippine Rise last year, is an underwater plateau located east of Isabela that is rich in pristine corals, diverse marine life and untapped gas reserves.

• READ: Benham's hidden gems: Thriving sea life, potential gas

The United Nations in 2012 declared it as part of the Philippines' extended continental shelf.

Golez said the Philippines' decision to allow China to survey the area gives Beijing an "opening" that could have "strategic implications" in terms of geopolitics.

"They want to go into the Western Pacific, which is right now dominated by the US, by Japan...That will enable them to do oceanographic studies to find out what is under the sea," he said.

China may also be looking for "thermocline," a thin layer hundreds of meters below the sea "where there's an abrupt change in temperature," allowing submarines to freely operate.

Golez also hit Presidential Spokesperson Harry Roque for saying the China was correct in saying the Philippines has sovereign rights, but not sovereignty over Benham Rise.

• 'China was right': Roque says PH has no sovereignty over Benham Rise

"When you are in dispute with another country, you never agree with that country…Never agree with your opponent because your opponent is going to quote you very liberally and very generously to our detriment," he said.

"The best is to emphasize that we have control over Benham Rise. We are the beneficial owner of Benham Rise because everything there, all natural resources are within our control," he added.