MANILA (AFP) - The United States has flown its most advanced surveillance plane from a military base in the Philippines over flashpoint areas of the South China Sea, Filipino authorities said Friday.

With Filipino soldiers on board, the US Navy flew the P-8A Poseidon from a former American airbase about 80km north of Manila and over the disputed sea on February 17, they said.

The Philippines is in the midst of a bitter row with China over competing claims to parts of the South China Sea that are close to the Philippine coastline.

"The objective is to patrol the South China Sea, to ensure freedom of navigation," Philippine military spokesman Colonel Restituto Padilla told reporters as he discussed the flight.

Philippine Navy spokesman Commander Lued Lincuna said the flight was a "familiarisation trip".

"They showed to us the surveillance capability of their aircraft, something that we do not have," Lincuna told AFP.

A US Navy statement also said the flight was meant to "increase understanding and showcase the capabilities" of what it said was its most advanced, long-range, anti-submarine, anti-surface warfare and surveillance aircraft.

"Sharing this aircraft's capabilities with our allies only strengthens our bonds," US Navy Lieutenant Matthew Pool, Combat Air Crew 4 patrol plane commander, said in the statement.

The Poseidon is "significantly quieter" and requires less maintenance compared with the older P-3 Orion surveillance plane, the statement said.

The Poseidon logged 180 flight hours while in the Philippines, from February 1 to 21, according to the statement.

It gave no further details about the flights, except for the single flight referred to by the Philippine military of the coast of Luzon island, which faces the South China Sea from its western coast.

China claims almost the entire South China Sea, which holds major sea lanes and is believed to contain vast oil and gas reserves.

Vietnam, Brunei, Malaysia, and Taiwan also have competing claims to parts of the sea.

The rivalries have for decades made the sea a potential military flashpoint, and tensions have risen significantly in recent years as China has sought to expand its presence in the region.

China has ramped up construction on reefs and islets, deployed more patrol vessels and taken control of a shoal within the Philippines' exclusive economic zone.

The Philippines, outmuscled by China, has sought military and diplomatic protection from the United States, its long-time ally.

It has also angered the Chinese government by asking a United Nations tribunal to rule on its dispute with China.