Taiwan's intelligence chief said Monday that China plans to build two aircraft carriers in addition to the first in its fleet, a refitted former Soviet carrier currently undergoing sea trials.

"Indeed the Chinese communists have decided to build two aircraft carriers on their own," Tsai Teh-sheng, head of the island's National Security Bureau, told parliament.

Tsai said that construction of the warships is slated to start in 2013 and 2015 respectively, with delivery dates of 2020 and 2022, and that they would be conventionally powered.

Tsai said that since mid-2011 China had conducted six sea trials of its first carrier, and that Taiwan expected it to go into service before the end of this year.

"Initially it may simply serve for training purposes but it can be transferred for battles when necessary in the future," he said.

The Chinese ship's sea trials have sparked international concern about China's widening naval reach amid growing regional tensions over maritime disputes and a US campaign to assert itself as a Pacific power.

Tsai's comments came in response to queries from Lin Yu-fang, a lawmaker from the ruling Kuomintang party who said the development could force Taiwan's entire defence strategy to be overhauled.

"Once the two warships join the Chinese navy, their threat to Taiwan will be way larger than that of the 'Varyag'," he said, referring to the reconditioned 1980s Soviet-era carrier.

In response to China's naval build-up, Taiwan is arming more of its warships with its new "carrier killer" anti-ship missiles and building a fleet of 12 corvettes designed with "stealth" technologies.

The Hsiung Feng (Brave Wind) missiles are reportedly designed to cruise at a speed of Mach 2.0, or twice the speed of sound, with a range of up to 130 kilometres (80 miles).

In an inauguration speech Sunday after winning re-election in January polls, Taiwan's President Ma Ying-jeou said his administration would maintain an "effective deterrent" while pursuing detente with China in the years ahead.

Ties between China and Taiwan have improved significantly since the Beijing-friendly Ma became the island's president in 2008, vowing to adopt a non-confrontational policy towards the mainland.

China still regards Taiwan as part of its territory awaiting reunification, by force if necessary, although the island has governed itself since the two sides separated in 1949 after a long civil war.