Manila will lease five military planes from Japan to patrol Philippine-claimed waters and outcrops in the disputed South China Sea, President Benigno Aquino announced Wednesday.

He said the leasing the TC-90 aircraft was part of government efforts to protect Philippine territory, which also included previously stated plans to acquire fighter jets and transport aircraft.

"Also lined up this year... is the lease of five of Japan's TC-90 training aircraft that would help our navy patrol our territory, particularly the West Philippine Sea," he said in a speech at an air force base near Manila.

"All of these additional equipment are part of our (Philippine Air Force) Flight Plan 2028, aimed at improving the capability of our air force to defend our territory," Aquino added.

The West Philippine Sea is the government's term for areas of the South China Sea that it claims as part of Philippine territory, including islands and reefs in the Spratly island group that it occupies.

Tensions in the South China Sea -- through which one-third of the world's oil passes -- have mounted in recent months since China transformed contested Spratly reefs into artificial islands capable of supporting military facilities.

China claims all of the Spratly islands, including those currently occupied by the Philippines.

Aquino has ramped up the upgrade of one of Asia's most badly equipped armed forces amid what his government sees as China's "illegal" bid to claim almost all of the South China Sea, including waters close to the coasts of neighbours.

Brunei, Malaysia, Taiwan and Vietnam also claim all or part of the Spratlys.

Japan's Maritime Self-Defence Force is known to have used the TC-90, a modified version of King Air C90 manufactured by US-based Raytheon Aircraft Co, as training aircraft.

Aquino's announcement followed the signing of an agreement last year between World War II foes Japan and the Philippines to transfer defence equipment to Manila.

Meanwhile a US general said Wednesday Washington is in talks to station its strike bombers in Australia amid concern about China's military expansion in the South China Sea.