Taiwan has begun mass production of a long-range missile and is developing three other models, a senior official said Thursday, in a rare admission of efforts to develop strike capacity amid growing Chinese pressure.

China, which claims democratic Taiwan as its own territory, has stepped up military activity near the island, as it tries to force the government in Taipei to accept Beijing's claims of sovereignty.

Taiwan's armed forces, dwarfed by China's, are in the midst of a modernization program to offer a more effective deterrent, including the ability to hit back at bases deep within China in the event of a conflict.

Taking lawmaker questions in parliament, Taiwan Defence Minister Chiu Kuo-cheng said developing a long-range attack capability was a priority.

"We hope it is long-range, accurate, and mobile," he said, adding research on such weapons by the state-owned National Chung-Shan Institute of Science and Technology had "never stopped."

Standing next to Chiu, the institute's deputy director Leng Chin-hsu said one long-range, land-based missile had already entered production, with three other long-range missiles in development.

Leng said it was "not convenient" for him to provide details on how far the missile could fly.

The institute, which is leading Taiwan's weapon development efforts, has in recent months carried out a series of missile tests off its southeastern coast.

Media in Taiwan have carried images of missiles launching and instructions have been given to aircraft to stay clear of the test area, but the tests have otherwise been shrouded in secrecy.

Taiwan's armed forces have traditionally concentrated on defending the island from a Chinese attack.

But President Tsai Ing-wen has stressed the importance of developing an "asymmetrical" deterrent, using mobile equipment that is hard to find and destroy, and capable of hitting targets far from Taiwan's coast.

Washington, Taipei's main foreign arms supplier, has been eager to create a military counterbalance to Chinese forces, building on an effort known within the Pentagon as "Fortress Taiwan."