The Philippines promised intensified sea patrols Tuesday as it welcomed the arrival of a second warship from the United States to bolster its defences during a maritime dispute with China.

President Benigno Aquino led the navy in welcoming the BRP Ramon Alcaraz, a Hamilton-class cutter that had been decommissioned by the US coast guard and acquired by Manila.

The ship berthed at Subic, a former American naval base on the west coast of the main island of Luzon facing the South China Sea where the Philippines has festering territorial disputes with China.

"Now that BRP Alcaraz has arrived, we will surely intensify our patrols in the Philippines' exclusive economic zone," Aquino said in a speech as the US envoy to Manila and other officials cheered.

"It will also boost our capability to counter any threat," he said.

Aquino made no direct reference to China, which has claims in the South China Sea overlapping those of the Philippines and other nations.

The Alcaraz, named after a Filipino commodore and World War II hero who battled Japanese warplanes, is the second warship acquired by the Philippines from its US ally in recent years, significantly upgrading its poorly-equipped military.

The first, BRP Gregorio del Pilar, was acquired in 2011 and immediately sent to patrol the country's waters to counter what the government says is increasing militarisation by China of the disputed areas.

In 2012 the Gregorio del Pilar confronted Chinese ships in a tense standoff at Scarborough Shoal, a small outcrop just off the coast near Subic.

The Chinese eventually gained control of the shoal after the Philippines backed down.

The 3,250-ton (2,950-tonne) Alcaraz can withstand strong waves and can stay longer at sea than any of the Philippines' current vessels, allowing for more extensive patrols, the navy said.

The Philippine military is considered one of the weakest in the region and it has been seeking more US aid to boost its capabilities.

The government last week said US military aid to Manila would increase more than 60 percent to 50 million dollars this year, with a possible acquisition of a third naval cutter.

Small numbers of US forces rotate for training in the Philippines, although the defence department has recently said it was in talks with its American counterparts for joint use of Philippine bases.

US Navy P3 Orion surveillance aircraft have also been helping the Philippines gather intelligence on what Manila has said is an increasing Chinese military build-up in the South China Sea.

China claims nearly all of the South China Sea, even waters close to its smaller neighbours. The dispute has long been considered a potential flashpoint of conflict in the region.

Subic, along with the nearby Clark air base, were longtime US military facilities, playing key roles from World War II to the Vietnam War and during the Cold War.

The Philippine Senate voted in 1991 to shut down US bases in the country.