MANILA - The Philippines has to explore with China oil and gas reserves believed to be sitting deep beneath the West Philippine Sea "unless other people step up," Foreign Affairs Secretary Teodoro Locsin Jr. said Wednesday.

Manila and Beijing, during President Rodrigo Duterte's visit to China last week, signed a deal on joint oil and gas exploration, and another on the Belt and Road infrastructure push, noted Locsin during a budget briefing before the House of Representatives' appropriations committee.

“We’re gonna have to do it with China unless other people step up the way Shell stepped up in Malampaya before,” Locsin said, referring to the gas field off Palawan where Shell Philippines Exploration BV leads the operating consortium.

The top diplomat said the oil and gas exploration deal would tap private enterprise in the Philippines.

“If in fact one side has no private enterprise, on our side it will be private enterprise. Businessmen know how to protect themselves,” he said.

He added that both agreements would be carried out within the bounds of the Philippine Constitution.

The Philippines and China have agreed to undertake joint oil and gas exploration at the West Philippine Sea, Manila's exclusive economic zone in the disputed South China Sea.

This even as China continued to assert indisputable sovereignty over nearly all of the resource-rich waters, ignoring the Philippines' July 2016 arbitration victory where a United Nations-backed tribunal invalidated Beijing's 9-dash line claim.

Following a meeting between Duterte and Xi in Beijing on Aug. 29, the two countries agreed to form working groups to explore commercial oil and gas agreements in the West Philippine Sea.

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Locsin, meanwhile, said that under the Belt and Road Initiative, where China offers financial assistance for other countries' infrastructure development, the Philippines "will never surrender a square inch of what we claim is ours."

This amid concerns that the initiative would be a debt trap.

Supreme Court Senior Associate Justice Antonio Carpio in March warned that China could seize natural gas deposits in the Reed Bank (Recto Bank) in the West Philippine Sea if the Philippines is unable to pay a $62-million Chinese loan for the Chico River irrigation project.

Both Manila and Beijing claim Recto Bank.

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Competing claims over the West Philippine Sea should not prevent both countries from other pursuits, said Locsin.

“That is no reason for us not to move forward on other fronts that are of mutual benefit to our countries," he said.

- Report from RG Cruz, ABS-CBN News