Cold War nuclear bomb blasted Australia

A nuclear bomb may have been detonated in the air over a Queensland rainforest at the height of the Cold War.

Declassified documents show that Britain, the United States and Australia set off a 50-tonne bomb in the rainforest at Iron Range, in north Queensland, in 1963, says the authoritative New Scientist magazine.

It was part of a secret military experiment codenamed Operation Blowdown.

The bomb was 25 times more powerful than the Oklahoma City bombing in 1995, which killed 168 people.

Its detonation was designed to test how the rainforest would react to the blast.

While the Australian documents describe the blast as testing the effect of a nuclear explosion, the British Government says it was a conventional bomb designed to simulate an air-detonated nuclear device.

A British Ministry of Defence spokeswoman said the bomb was made of TNT and detonated close to the ground to simulate the effects of a 10-kilotonne nuclear explosion in the air.

"There was no radiation hazard," she claimed.

But declassified records in the National Archives of Australia describe Operation Blowdown as "an investigation into the effect of nuclear explosions in a tropicalforest."

And a medal citation for an Australian sergeant in charge of the operation explicitly refers to it as "an airburst nuclear device."

Brian Stanislaus Hussey was awarded the British Empire Medal in 1965 for supervising Army equipment during Operation Blowdown.

He died three years later at the age of 45 from multiple cancers.

His daughter, Marie Strain, blames the operation for her father's death.

"I want to know why the nuclear tests had to be done," she said.

Lockhart River councillor Noel Accoom said yesterday that the community knew of the bomb site, only a few kilometres from the town, and a number of bunkers in the area.

"It's a big, flat area that looks like it has been blown up," Mr Accoom said.

He said officials moved people away from the region during tests.

The bombed area was on national park and council land.

Mr Accoom said he did not know of any after-effects from the tests or whether nuclear devices were used.

Reports of the blast are the latest in a string of revelations about British nuclear testing in Australia in the 1950s and 1960s.

Recently declassified documents reveal that soldiers walked, crawled and drove through nuclear fallout to test protective clothing and that tonnes of depleted uranium were detonated in the air above test sites.

Last week, it was claimed that profoundly disabled people were sent from institutions in Britain to be used as guinea-pigs during 1950s tests in the Australian desert.

They did not return home and are assumed to have died after the tests in Maralinga, South Australia.

At least six New Zealanders were exposed to radiation at the test sites in Australia.

Hundreds more New Zealand Navy officers and crew sailed into nuclear test zones around Christmas (now Kiritimati) and Malden Islands.

The NZ veterans are awaiting legal advice on which to base a lawsuit challenging Britain's denial that the testing programme caused health problems in Commonwealth forces.