MANILA -- China's promise of economic aid is "a pittance" compared to the resources that it lays claim to in the West Philippine Sea, Retired Supreme Court Senior Associate Justice Antonio Carpio said Monday.

Beijing is claiming 80 percent of the Philippines' Exclusive Economic Zone (EEZ) as part of its nine-dash line, equivalent to about 300,000 square kilometers, larger than the total land area of the Philippines, he said.

"How can you say that they are our friend when they are grabbing our backyard? They’re grabbing our fish, gas and all our natural resources. This is the biggest threat to Philippine national security at present and in the next 25 to 50 years," Carpio told ANC.

"We are going to lose a maritime space larger than our total land area. What Philippine leader can explain that to future generations of Filipinos... We have to stand pat on this. We owe it to this country, we owe it to future generations of Filipinos," he added.

President Rodrigo Duterte previously shelved the 2016 arbitral award that junked China's "historic claims" to the West Philippine Sea, as he pursued loans and investments from Beijing.

Beijing has promised $24 billion in loans and investments to the Philippines, of which only 5 percent has materialized. "Even if the entire $24 billion has materialized, that’s a pittance compared to the value of the fish, oil, gas and other mineral resources in the West Philippine Sea," said Carpio.

The Philippines has also stopped benefiting from Chinese tourists, who have stopped coming due to lockdowns meant to curb the coronavirus pandemic, he said.

China also deems Philippine Offshore Gaming Operators or POGOs as illegal and has stopped issuing passports to their workers, he said.

"There are no loans and investments, as promised. No tourists, no POGOs. What can we get out of this? Nothing. We have set aside the ruling for nothing. That is the way China is trying to win: by promising something and delivering nothing," Carpio said.

Duterte last week told the UN General Assembly that the Philippines "firmly rejects" any attempt to undermine the ruling.

Manila can rally an "overwhelming majority" of allies if it raises its arbitral triumph against Beijing before the United Nations, said Carpio.

• Philippines can rally 'overwhelming majority' vs China before UN: Carpio

-- With a report from Jamaine Punzalan, ABS-CBN News