AN Australian commander's fatally flawed decision to lay a minefield in Vietnam in 1967 cost the lives of at least 60 of his own men and maimed hundreds of others, new research has revealed.

Five sappers died in May 1967 planting 21,048 American-made M16 "jumping jack" mines, which were intended as a barrier to prevent the Viet Cong infiltrating villages in Phuoc Tuy province, close to the Australian military base at Nui Dat in southern Vietnam.

Dozens more Australians were killed in subsequent assaults on Viet Cong positions surrounded by M16 mines stolen from the Australian-laid minefield.

The mines were laid on the orders of Brigadier Stuart Graham, who went against the advice of his predecessor and other senior military advisers in the mistaken belief the barrier would stop a Viet Cong advance.

Details of the ill-fated mission have been uncovered for the first time by military historian Greg Lockhart, whose painstaking study of official records, many of them only recently declassified, revealed what he describes as the greatest Australian military bungle since World War II.

His research reveals that M16 mines planted on Brigadier Graham's orders were responsible for 12 per cent of Australian casualties in Vietnam from May 1967 to the withdrawal in 1971. Of the more than 50,000 Australians sent to Vietnam, 520 were killed.

"The mines not only gave the enemy their No1 armament but when they laid them against us it helped the local VC leaders organise the population," Dr Lockhart told The Weekend Australian.