Vietnam's military says a helicopter has crashed on a training mission, killing all four soldiers aboard.

Lt. Gen. Vo Van Tuan, army deputy chief of staff, said the UH-1 chopper crashed on a farm on the outskirts of Ho Chi Minh City on Wednesday.

Tuan says the helicopter disappeared from radar about eight minutes after taking off.

He says the helicopter had belonged to American forces in Vietnam but was seized by communist forces after the war ended in 1975.