Marcos has sought to deepen defence cooperation with the United States as he stands up to Chinese actions in the South China Sea, which Beijing claims almost entirely.

"China's determining influence over the security situation and the economic evolution of this region is a permanent fact," Marcos said in a speech at the Shangri-La Dialogue in Singapore, a major security forum attended by defence ministers from around the world.

"At the same time, the stabilising presence of the United States is crucial to regional peace. It's never a choice. Both countries are important."

The Philippines, a treaty ally of the United States, is a key focus of Washington's efforts to strengthen alliances and partnerships in the Asia-Pacific region as it seeks to counter China's growing military might and influence.

Given its position in the South China Sea and proximity to self-ruled Taiwan, which China claims as its own, Philippine support would be crucial for the United States in the event of any conflict.

The Philippines expanded a 2014 agreement last year to give US military access to another four of its military bases, taking the total number to nine, including two in the far north of the country, less than 450 kilometres (280 miles) from Taiwan.

The Enhanced Defence Cooperation Agreement (EDCA) allows US troops to rotate through and store defence equipment and supplies.

The United States' growing presence in the region and its regular deployment of warships and fighter jets in the Taiwan Strait and South China Sea have infuriated China's leaders in Beijing.

China has accused the United States of using the Philippines as a "pawn to stir up trouble in the South China Sea".

Manila and Beijing have a long history of maritime territorial disputes, but tensions have worsened under Marcos, who has insisted the Philippines will not give up a "square inch of our territory".

Marcos said on Friday that the South China Sea dispute is an issue that goes beyond the Asia-Pacific region.

"The peace and stability of the South China Sea and the freedom of navigation in the South China Sea is a world issue," Marcos said.

"It is not just (about) ASEAN member states. It is quite easy to see that it is in fact the world that has become the stakeholder."