The F-16V, one of Taiwan's most advanced fighter jets, disappeared from radar screens around half an hour after taking off for a routine training flight from a base in the city of Chiayi, the air force said.

The pilot was identified as 28-year-old captain Chen Yi, who joined the air force in 2020.

Taiwan's national rescue centre reported that people saw the jet "crashing into the sea", which the air force confirmed at a press briefing.

The F-16V "rapidly fell into the sea at a large angle and there's no sign that the pilot parachuted out," said air force inspector-general, Major General Liu Hui-chien, adding that all F-16 fighters had been grounded.

The incident came less than two months after Taiwan commissioned its first squadron of US-made F-16V fighters in an effort to upgrade its ageing fleet as tensions with China spike.

Beijing claims self-ruled Taiwan as part of its territory and has vowed to take it one day, by force if necessary.

President Tsai Ing-wen has ordered an all-out rescue effort and asked for clarity around the cause of the incident, her office said.

At least three helicopters and five coastguard vessels had been dispatched to find the jet.

"The air force and coastguard are making our best efforts to continue the rescue mission... but it's difficult at night with choppy sea," Liu said.

The F-16V is an upgraded and much more sophisticated version of the island's other F-16 fighters, which date back to the 1990s.

Taiwan also has French-made Mirage jets and its own warplanes.

The air force has suffered a string of fatal accidents in recent years as it faces growing pressure from China.

Last March, Taiwan grounded all military aircraft after a pilot was killed and another went missing when their fighters collided mid-air in the third fatal crash in less than six months.

Eight senior officials, including the chief of general staff, were killed in a helicopter crash in January 2020.