MANILA - The Philippines will lose a maritime area larger than its total land area to China if it does not defend its exclusive economic zone (EEZ), former Senior Associate Justice Antonio Carpio warned Thursday.

Carpio made the remark as he called on President Rodrigo Duterte to "love the Filipino people, not President Xi Jinping."

"If we do not act as one, if we do not exert all effort, exhaust all remedies, we will lose 80 percent of our EEZ in the West Philippine Sea. We will lose a maritime area larger than our total land area," he told ANC's Headstart.

"We are depriving future generations of Filipinos the marine wealth that is found in this huge maritime area that we will lose to China...The President should love the Filipino people, not President Xi Jinping."

The Philippines should build structures in its EEZ and send its Navy to patrol the area, Carpio said.

• PH should join freedom of navigation patrols, form alliance vs China 9-dash line: Carpio

"It's really up to us. If we want to defend, we can defend, we have allies, we have the MDT (Mutual Defense Treaty). We can send ships and if they are attacked we can invoke the treaty," he said.

"That’s why China has not attacked BRP Sierra Madre...China knows the consequence, China doesn’t want the US to intervene and we must take advantage of that. There's no occasion for us to invoke the treaty because we don’t patrol the area."

Beijing is ramping up its militarization in the West Philippine Sea as Duterte nears his end of term, according to Carpio.

"In the Asia-Pacific region, they were able to accelerate their timetable because of people like President Duterte who has cooperated with them," he said.

"Vietnam, Malaysia they are strong in defending their EEZ. They face off the Chinese in the high seas but their economic relations continue. We're afraid to even talk, the President is completely silent, radio silence, because he says 'I don’t want to go to war, I want loans and investments from China.'"

China used threat of war when it chased off a Filipino civilian boat carrying fishermen and the ABS-CBN News team in the West Philippine Sea, Carpio said.

The Philippines should file a case against China before the arbitral tribunal but it cannot do so without Duterte's approval, he added.

"They're using a gray zone so we can’t invoke the treaty. You cannot use threat of war or threat of force or act of force to settle a dispute, you must go through negotiation or arbitration," he said.

"Because he’s the chief architect of the foreign policy, we cannot file a case without his consent, his approval. He’s the one blocking what could defend the West Philippine Sea because he wants to appease China."

China will only agree to a Code of Conduct when it finishes its reclamation in the disputed sea, Carpio said.

• China 'delaying' sea code of conduct until reclamation is complete: Carpio

"From the very start, China said we will sign a COC at the appropriate time. When is the time right for China? When China has completed all of its artificial islands," he said.

"That will legitimize what they have built. China will use the Code of Conduct to legitimize its structures in the South China Sea."

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