The Philippines armed forces will guarantee the "unimpeded and peaceful" exploration and exploitation of natural resources within the country's exclusive economic zone (EEZ) as it shifts its focus to external defence, Manila's defense secretary said.

"We are evolving into a defence concept which projects our power into areas where we must, by constitutional fiat and duty, protect and preserve our resources," Defense Secretary Gilberto Teodoro told the Manila Overseas Press Club on Tuesday night.

Teodoro also said the Philippines will "increase the tempo" of activities with allies and major partners in the West Philippines Sea and other parts of the country and "exercise these partnerships to the full".

Manila calls the portion of the South China Sea that is within its EEZ as the West Philippine Sea, where it has had a series of confrontations with China with both trading accusations of provoking conflict.

In addition to the Philippines, Vietnam, Indonesia, Malaysia and Brunei claim parts of the South China Sea disputed by China, which claims almost all of the sea, a conduit for more than $3 trillion of annual ship-borne commerce.

The Permanent Court of Arbitration in 2016 said China's claims had no legal basis, a ruling Beijing rejects.

Plans by a Philippine firm to drill for oil and natural gas on the Reed Bank in the South China Sea have been hampered for years by the territorial dispute.

"We are not the ones encroaching on the EEZ of another country sea. The encroacher has a vast area of sea," Teodoro said. "We do not want a fight, we want peace but it should be based on international law and sustainability."

"We will not bend over backward," Teodoro said.

China and the Philippines agreed last week to improve maritime communication and to properly manage conflicts and differences in the South China Sea through friendly talks.