Rivals United States and China are expected to try to woo the Philippines into their side but the country prefers to advance its own interest and seek a rules-based resolution to the South China Sea issue, Malacañang said Tuesday.

Presidential spokesman Harry Roque made the statement after United States Secretary of State Mike Pompeo rejected  Beijing's claims to the resources in the South China Sea as illegal.  Pompeo likewise backed the Philippines and other Southeast Asian allies in protecting their sovereign rights to their offshore resources.

"The great powers as they escalate their rivalry will woo us into their side, we will be sure that we will advance our national interest," Roque said during a televised briefing, reacting to Pompeo's statement.

"Meanwhile we want all parties involved to abide with the rule of law particularly with the UN Convention on the Law of the Sea," he said.

Roque also echoed President Duterte's position calling for the completion of a code of conduct to reduce tension in the disputed waters. 

"Ang importante po ngayon atupagin natin iyong pagbubuo at pagpapatupad ng code of conduct nang maiwasan po iyong tensyon sa lugar na iyan (The important thing now is to complete and implement the code of conduct to avoid tension in the area)," he said.

The United States has waded into the South China Sea conflict after insisting that China's claims to offshore resources in the South China Sea are "completely unlawful."

Pompeo, in a statement posted on the US State Department website, said  China has "no legal grounds to unilaterally impose its will on the region," citing the arbitral ruling that nullified its nine-dash claim in the area.

He also said China cannot lawfully assert a maritime claim over the Spratly Islands and other reefs that fall under the Philippines' sovereign rights and jurisdiction. "Beijing’s harassment of Philippine fisheries and offshore energy development within those areas is unlawful, as are any unilateral PRC actions to exploit those resources," he said.

Pompeo said the world will not allow Beijing to treat the South China Sea as its "maritime empire.”

"America stands with our Southeast Asian allies and partners in protecting their sovereign rights to offshore resources, consistent with their rights and obligations under international law," he added.

China and four Southeast Asian nations, including the Philippines, Brunei, Malaysia and Vietnam, have overlapping claims in the resource-rich South China Sea. Tension in the region has risen as countries protested China's increased reclamation works and military buildup in the disputed waters.