Taipei - An Indigenous Defence Fighter jet of Taiwan's air force went missing Monday during routine training over the island of Penghu, a spokesman said.

"We lost contact with the fighter jet shortly after it flew from Chingchuankang air base (central city of Taichung) at 9 am (0100 GMT) to Penghu," said air force training director Chang Chao-hui.

He said two officers, identified as 29-year-old Captain Kuo Chih-pin and 31-year-old Captain Chen Chien-ting, were on board the plane when it went missing over the sea.

Chang said the military has already sent six vessels and two helicopters to search for the plane, developed by Taiwan in the 1990s with US technology.

The military initially ruled out weather and engine trouble as the likely causes because visibility over Penghu was clear while the fighter jet, which just completed full-scale maintenance, was in good condition, he said. (dpa)