HANOI (AFP) - Three people were killed when their army helicopter crashed in a mountainous area of southern Vietnam, the defence ministry said on Wednesday (Oct 19), the latest in a string of deadly military aircraft accidents.

The Airbus EC130 helicopter disappeared from radar just 23 minutes after take-off on Tuesday in Ba Ria-Vung Tau province with a pilot and two trainees on board.

"Rescue forces exerted all efforts to locate the helicopter crash on Bao Quan mountain," the defence ministry said in a statement.

"All the three men from the flight training team were found dead," it said, adding an investigation into the cause of the crash was under way.

A total of 14 people have now been killed in four military aviation accidents this year.