Taiwan may build its own submarines, a top military officer said Thursday, in a sign that patience is wearing thin after a US offer to sell the island eight submarines has been stalled for a decade.

Chao Shih-chang, a deputy defence minister, told parliament the ministry has continued pushing for the sale since the United States promised eight conventional submarines in 2001.

But while waiting for the US to follow through on the deal, the ministry has also been evaluating calls for the construction of the submarines by the island's leading shipyard CSBC Corporation, Taiwan.

"If it can reach the necessary technological level and obtain support from abroad, the defence ministry would certainly be pleased to see CSBC Corporation, Taiwan build the subs," Chao said.

In April 2001, then US president George W. Bush approved the sale of eight conventional submarines as part of Washington's most comprehensive arms package to the island since 1992.

Since then, however, there has been little progress as the United States has not built conventional submarines for more than 40 years and Germany and Spain had reportedly declined to offer their designs for fear of offending China.

The Taiwanese navy currently operates a fleet of four submarines, but only two of them, Dutch-built, could be deployed in the event of war. The other two were built by the United States in the 1940s.

Tensions between Taiwan and China have eased markedly since President Ma Ying-jeou came to power on a platform of beefing up trade links and allowing more Chinese tourists to visit. Ma was re-elected in January.

But Taiwan, which has governed itself since 1949, still sees a need to modernise its armed forces because China regards the island as part of its territory awaiting reunification, by force if necessary.