TAIPEI (Reuters) - China is building two aircraft carriers that will be the same size as its sole carrier, a 60,000-tonne refurbished Soviet-era ship, according to a new Taiwanese Defense Ministry report on the capabilities of the People's Liberation Army (PLA).

Little is known about China's aircraft carrier program, which is a state secret, although Chinese state media have hinted new vessels are being built. The Pentagon, in a report earlier this year, said Beijing could build multiple aircraft carriers over the next 15 years.

One of the new vessels is being built in Shanghai and the other in the northeastern city of Dalian, said the Taiwanese report, which was obtained by Reuters.

It gave no estimate for when construction would be finished.

The Chinese Defense Ministry did not immediately respond to a request for comment. China is on a three-day national holiday to commemorate victory over Japan in World War Two.

A Taiwanese Defense Ministry spokesman said details on the carrier program came from the ministry's intelligence unit. He declined to give further details on the report, which was sent to parliament this week.

Taiwanese intelligence agencies closely monitor Chinese military developments because Beijing has never renounced the use of force to take back what it deems a renegade province.

As carriers are commissioned for service into China's navy, a command unit would be set up with "the goal to unify power and accelerate combat capabilities", the report added.

The Liaoning, a carrier bought from Ukraine in 1998 and refitted in China, has taken part in military exercises, including in the disputed South China Sea, but is not yet fully operational.

Successfully operating the Liaoning is the first step in what some military experts believe will be the deployment of Chinese-built carriers by 2020.

The Taiwanese report added that of China's 1.24 million-strong ground forces, 400,000 could be used in combat against the island.

Chinese special forces had held mock battles at the Zhurihe training base in Inner Mongolia using a full-scale model of Taiwan's presidential office and nearby government buildings and roads, the report said.

The PLA's Second Artillery Force and bombers had also practiced attacks in an area near Dingxin air force base in Gansu province that is modeled on Taichung Airport in central Taiwan, which is used for both commercial and military purposes, the report said.

China-Taiwan ties have generally improved under Taiwan President Ma Ying-jeou, but China has maintained that any declaration of independence or moves toward independence would prompt it to use force to take back the island.

Taiwan has been self-ruled since 1949 when Chiang Kai-shek fled to Taiwan with his Nationalist forces after losing a civil war with Mao Zedong's Communists.