The Philippines will hold joint naval drills with the United States, Japan and Australia, two diplomatic sources told AFP Thursday, as the four countries deepen military ties to counter China's expanding influence in the Asia-Pacific region.

The exercise will be held Sunday in the disputed South China Sea -- which Beijing claims almost entirely -- days before US President Joe Biden is due to hold the first trilateral summit with the leaders of the Philippines and Japan.

The diplomatic sources spoke on condition of anonymity because the drills have not yet been officially announced.

Earlier this week, the Australian warship HMAS Warramunga arrived at the Philippine island province of Palawan, which faces the hotly contested waters.

The Philippine military said the visit was "aimed at strengthening military relations with partner nations".

Regional tensions have escalated in the past year as China becomes increasingly confident in asserting its claims over waters also claimed by the Philippines and Japan, as well as over self-ruled Taiwan.

In response, the United States has sought to strengthen its alliances in the region, including with its treaty allies Japan and the Philippines.

Biden's summit with Philippine President Ferdinand Marcos and Japanese Prime Minister Fumio Kishida at the White House on April 11 is the latest in a series of meetings with Asia-Pacific partners.

Biden will also hold separate bilateral meetings with Marcos and Kishida.

The exercise and summit follow repeated confrontations between Chinese and Philippine vessels near disputed reefs off the Southeast Asian country in recent months.

Top US officials have repeatedly declared the United States' "ironclad" commitment to defending the Philippines against an armed attack in the South China Sea.

Meanwhile, talks between the Philippines and Japan for a defence pact that would allow the countries to deploy troops on each other's territory were "still ongoing", a spokesman for the Philippine foreign affairs department told reporters Thursday.

Manila already has a similar agreement with Australia and the United States.