TAIPEI, Dec 1 (Reuters) - Test flights for delayed F-16V fighter jets for Taiwan are due to start this month, with 54 of the 66 aircraft ordered now in production, the head of the island's air force said on Monday.

Taiwan, which faces a rising military threat from Beijing, has complained of repeated delays to weapons ordered from the United States, the Chinese-claimed island's most important international backer and arms supplier.

The United States in 2019 approved an $8 billion sale of Lockheed Martin LMT.N F-16 fighter jets to Taiwan, a deal that would take the island's F-16 fleet to more than 200 jets, but the project has been hit by issues including software problems.

Speaking to lawmakers in parliament, Air Force Chief of Staff Lee Ching-jan said 54 aircraft were now on the production line, up from 50 in October.

Flights tests are due to begin this month, he added.

Lockheed said last month it was working to accelerate delayed deliveries to Taiwan of the F-16Vs.

The F-16Vs have advanced avionics, weapons and radar systems to better face down the Chinese air force, including its stealthy J-20 fighters.

(Reporting by Ben Blanchard and Roger Tung; Editing by Michael Perry)

((ben.blanchard@thomsonreuters.com;))