The Philippine military said today it had evaded a Chinese sea blockade by using an airplane to drop food to soldiers on a tiny and remote South China Sea shoal claimed by both countries.

The incident was the latest to escalate tensions between the Asian nations over their conflicting claims to parts of the South China Sea, a major sealane and rich fishing ground that is believed to hold vast mineral resources.

"We confirmed there was an airdrop of food to our troops," Defence Department spokesman Peter Paul Galvez said.

He said the airdrop was "via airplane," but did not say when it occurred nor give further details.

The incident took place at Second Thomas Shoal in the Spratly island group, which is around 200 kilometres (125 miles) from the western Philippine island of Palawan and which Manila insists is part of its continental shelf.

The shoal is more than 1,000 kilometres from Hainan island, the closest Chinese landmass, but China claims nearly all of the South China Sea based on what it says are historical records.

A tiny unit of Filipino marines live on the BRP Sierra Madre, a decrepit, beached former World-War-II US navy transport ship that was transferred to the Philippine navy and run aground on the shoal in the 1990s.

Troops on the 1,000-metre (3,280-foot) long ship have ever since guarded the shoal.

China has long demanded the Philippines pull out the vessel and the marines.

But the Philippines said this week that Chinese coastguard ships blocked two Philippine-flagged civilian vessels on March 9 as they were carrying supplies and personnel to the shoal.

The Philippines said this was the first time there had been such Chinese resistance.

The Philippines issued a diplomatic protest over the incident, but China in response reiterated its position that the shoal was Chinese territory.

The Philippines and China, along with Brunei, Malaysia, Taiwan and Vietnam all claim parts or all of the South China Sea.

The Philippine government has accused China of becoming increasingly aggressive in asserting its claims to the sea. Last year it initiated United Nations arbitration to settle the dispute, but China refused to participate.

The Philippines also last month accused Chinese ships of using a water cannon to drive away Filipino fishermen who were approaching Scarborough Shoal, another South China Sea outcrop.