A remote outpost on Second Thomas Shoal has been a focus of clashes between Chinese and Philippine ships in recent months as Beijing steps up efforts to push its claims to almost the entire South China Sea.

A Filipino sailor lost a thumb in the latest June 17 confrontation when Chinese coast guard members wielding knives, sticks and an axe foiled a Philippine Navy attempt to resupply its troops.

Sunday's announcement follows talks between the Philippines and China this month when they agreed to increase the number of communication channels to resolve maritime disagreements between them.

"The Philippines and the People's Republic of China have reached an understanding on the provisional arrangement for the resupply of daily necessities and rotation missions to the BRP Sierra Madre in Ayungin Shoal," the Philippine foreign ministry, using the Filipino name for Second Thomas Shoal.

The foreign ministry did not provide details of the arrangement, but said both sides recognised the need to "de-escalate the situation in the South China Sea and manage differences through dialogue and consultation".

China's embassy in Manila did not immediately respond to requests for comment.

A handful of Filipino troops are stationed on the rusty BRP Sierra Madre warship that was deliberately grounded on Second Thomas Shoal in 1999 to assert Manila's claims to the area.

They require frequent resupplies for food, water and other necessities as well as transport for personnel rotations.

Earlier Sunday, Manila said the resupply missions would remain a Philippine operation, after Washington vowed to "do what is necessary" to support them.

"As far as the RORE (rotation and resupply mission) is concerned, we're keeping it as a purely Philippine operation utilising Philippine ships, personnel and leadership," National Security Council assistant director-general Jonathan Malaya told AFP.

"That may change depending on the guidance from top management but that's the direction or policy at present."

Malaya's remarks came after White House National Security Adviser Jake Sullivan said the United States "will do what is necessary" to ensure the Philippines can continue to resupply its troops on the contested atoll.

"We will continue to support the Philippines and stand behind them as they take steps to be able to ensure that," Sullivan said during the Aspen Security Forum conference in Colorado.

Malaya said the National Security Council appreciated the US offer and the Philippines would continue consultations as treaty allies.

Manila has a mutual defence pact with the United States which requires both parties to come to the other's defence in case of an "armed attack" against vessels, aircraft, military and coast guard anywhere in the Pacific theatre, which Washington says includes the South China Sea.