Taiwan is considering extending the runway on the contested Spratly island in a move that could provoke fresh tensions in the heavily disputed South China Sea, media reported on Sunday.

If approved, the project would extend by 500 metres (1,640 feet) the runway on Taiping Island, the largest in the disputed waters and some 860 miles (1,376 kilometres) from Taiwan, the Liberty Times said.

"The national security authorities lately convened a meeting to evaluate the proposal as the situation in the South China Sea has been getting ever complicated," it cited an unnamed national security source as saying.

Tensions in the South China Sea have risen recently, with China and the Philippines locked in a maritime dispute over the Scarborough Shoal, a reef off the Philippine coast.

The runway, currently 1,150 metres (3,773 feet), was built in 2006 despite protests from other countries with claims in the potentially oil-rich area, including Vietnam, Brunei, China, Malaysia and the Philippines.

Calls for an increase of Taiwan's defence capability on the disputed area have been on the rise as the claimants have deployed more troops and added military facilities there.

In May Taiwan's coastguards said that the number of intruding Vietnamese boats surged to 106 last year, up from 42 the previous year.

In the same month Taiwan formed a special airborne unit capable of scrambling to the South China Sea in just hours, after a visit by three legislators and several top military officers in a trip intended to renew their territorial claim amid mounting tensions in the area.

All claimants except Brunei have troops based on the archipelago of more than 100 islets, reefs and atolls, which have a total land mass of less than five square kilometres (two square miles).