The Philippines said Friday it plans to give the United States access to five military bases under a deal that could see US forces return to their giant former facility at Subic Bay.

An access deal signed last week would allow the US to rotate more aircraft, ships, equipment and troops over the next 10 years at unspecified bases in the territory of the Asian ally strategically facing the South China Sea.

The two countries are now in follow-up talks to select the Filipino bases, said defence undersecretary Pio Batino, the chief Filipino negotiator.

"Right now, the discussions would be ranging from three to five (Filipino military) bases," he told reporters.

"That's not the final, but that is the starting discussion point."

The Philippines is offering Fort Magsaysay, a sprawling army base about 100 kilometres (62 miles) north of Manila that regularly hosts annual large-scale US-Filipino military exercises, Batino said.

He added "limited portions of Subic" would also be offered, but declined to identify the three other bases under consideration.

The Philippines intends to conclude the discussions not later than September 30, Batino added.

The deal for increased US access is part of Philippine efforts to boost its weak military capabilities at a time of deep tensions with China over competing claims to parts of the South China Sea.

China claims most of the sea, even waters close to the Philippines and other countries in the region.

Subic, facing the South China Sea, was the former repair yard of the Japan-based US Pacific fleet.

American forces vacated it in 1992, along with nearby Clark Air Base, after the Philippine Senate refused to extend a bases treaty, ending nearly a century of major US military presence.

It is now a civilian free port, but maintains a US-era military runway and a deep harbour that is still used by American warships stopping over for military exercises or for regular provisioning.

Bound by a mutual defence pact, the US and the Philippines engage in regular war games that see thousands of US troops and state-of-the-art American military hardware brought to the Philippines.

The Philippines signed the bases access deal last week, hours ahead of a state visit to Manila by American President Barack Obama.

The deal also allows the US to build structures inside the bases for use by its forces, as well as to store supplies and equipment.