The single-engine propeller plane went down at 8:08 am (0008 GMT) at the northern end of the runway at Gangshan Air Base in the island's southern port city of Kaohsiung, the air force said.

A task force has been set up to investigate the cause of the crash, which took place about 20 minutes after takeoff.

The pilots, both lieutenant colonels and aged 41 and 45, had not reported any problems with the aircraft in the moments leading up to the crash, said the air force's inspector general, Major General Chiang Yi-cheng.

"Throughout the entire flight there were no abnormal radio communications before the accident occurred," Chiang told a news conference.

President Lai Ching-te said he was "deeply saddened" at the loss of life, describing the pilots as "heroic" and thanking them for their "sacrifice and dedication" to Taiwan.

The Taiwanses air force uses Beechcraft single-engine propeller planes as the primary trainer aircraft for its pilots, according to the defence ministry's website.

The planes were first delivered to Taiwan in 1984.

In January, an F-16 fighter jet crashed into the sea off eastern Taiwan during a routine training mission. The pilot is believed to have ejected from the aircraft but has not been found.