Two American fighter jets dropped four bombs on the Great Barrier Reef after a training exercise went wrong, it has emerged.
US officials said the pilots of two AV-8B Harrier jets were forced to jettison the unarmed devices on Tuesday because both aircrafts were running low on fuel and could not land with the bombs on board.
The pilots intended to drop the munitions on a designated bombing range on Townshend Island but aborted the mission when controllers reported the area was not clear of hazards.
Instead, they jettisoned two bombs from each aircraft on the World Heritage-listed marine park off the coast of Queensland state.
The pilots tried to minimise the damage by releasing the devices over deep water of more than 164 feet (50 meters) and away from coral reefs, officials said.
All four bombs were inert and so did not explode. It is unclear whether any environmental damage was caused.
An Australian Defence Force spokesman was quoted as saying the bombs posed "minimal risk or threat to the public, the marine environment or civilian shipping transiting the reef area".
The two jets were launched from aircraft carrier USS Bonhomme Richard during a three-week joint military training exercise involving around 28,000 US and Australian personnel.
Graeme Dunstan, who is among the environmentalists and anti-war activists protesting against the joint exercise, claimed the US military could no longer be trusted to protect the environment.
"How can they protect the environment and bomb the reef at the same time? Get real," Mr Dunstan said from the Queensland coastal town of Yepoon near where the military exercise is taking place.
The Great Barrier Reef is the world's largest network of coral structures rich in marine life that stretches more than 1,,800 miles (3,000 kms) along the Australian northeast coast.