The Philippines and the United States will kick off the largest-ever joint military drills in the archipelago nation next week, US officials said Tuesday, showing off their strong defence ties in the face of growing Chinese assertiveness.

Nearly 9,000 Filipino and American soldiers will take part in the 12-day war games on the main island of Luzon, which are usually an annual affair but were cancelled or curbed during the pandemic.

The exercises, which start March 28, will cover among other things maritime security, live-fire training, counterterrorism, and humanitarian assistance and disaster relief, the US embassy said in a statement.

"(Both sides) will train together to expand and advance shared tactics, techniques and procedures that strengthen our response capabilities and readiness for real-world challenges," said Major General Jay Bargeron, commander of the US 3rd Marine Division.

Recent manoeuvres between the longtime allies have focused on potential conflict in the South China Sea, which Beijing claims almost in its entirety.

China has ignored a 2016 ruling by The Hague-based Permanent Court of Arbitration that its historical claim is without basis.

American and Filipino troops have typically conducted war games together annually, though the event was cancelled or curbed during the Covid-19 pandemic
American and Filipino troops have typically conducted war games together annually, though the event was cancelled or curbed during the Covid-19 pandemic AFP / TED ALJIBE

It has reinforced its stance by building artificial islands over some contested reefs and installing weapons on them.

The Philippines, Brunei, Malaysia, Taiwan and Vietnam also have competing claims over the waters.

Tensions between Manila and Beijing spiked last week after the Philippines confronted China's ambassador over a Chinese navy ship caught illegally "lingering" in its archipelagic waters.

The exercises will also be held in the shadow of the Russian invasion of Ukraine, where the US and its allies are providing defensive weapons to Kyiv and imposing crippling economic sanctions on Moscow.

President Rodrigo Duterte expressed concern Monday that the Philippines was "involved" in the conflict because of its security alliance with the United States.

That includes a mutual defence treaty and permission for the US military to store defence equipment and supplies on several Philippine bases.