The United States, Australia, Japan, and the Philippines will hold joint naval and air drills in the disputed South China Sea on Sunday, their defence chiefs said in a statement, as they deepen ties to counter China's growing assertiveness in the region.

The exercise will take place in the disputed waterway -- 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.

"Our combined defense/armed forces will conduct a Maritime Cooperative Activity within the Philippine Exclusive Economic Zone on April 7, 2024," they said in a joint statement Saturday.

They said it would demonstrate the allies' "collective commitment to strengthen regional and international cooperation in support of a free and open Indo-Pacific."

The drills named the "Maritime Cooperative Activity" will include naval and air force units from all four countries, the joint statement said. 

The four defence chiefs said they would "strengthen the interoperability of our... doctrines, tactics, techniques, and procedures." 

There were no details on what the drills would precisely include.

The Japanese embassy in Manila said in a statement that "anti-submarine warfare training" would be included in the drills.

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

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

China has blamed the Philippines for raising tensions in the hotly contested waterway, where Beijing and Manila have a long history of maritime territorial disputes.

'Peace and stability'

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

"These activities with our allies Australia, Japan, and the Philippines underscore our shared commitment to ensuring that all countries are free to fly, sail, and operate wherever international law allows," US Defense Secretary Lloyd Austin said in the joint statement. 

"Our operations together support peace and stability at the heart of our shared vision for a free and open region."

Marcos issued a strongly worded statement on March 28, vowing the Philippines would not be "cowed into silence, submission, or subservience" by China.

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 Department of Foreign Affairs said. 

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

In an interview with the Nikkei business daily on Thursday, Kishida said Japan needs to show a bigger presence and "take greater responsibility" for providing options for the Philippines and other Southeast Asian countries.  

He also said Tokyo, Washington and Manila "will work together to proceed with trilateral cooperative projects", including in semiconductors, digital technology and next-generation nuclear energy.