The Australian defence department on Monday denied testing the powerful defoliant Agent Orange in rainforest near a town in the country's far northeast during the Vietnam War.
Defence officials were asked to investigate whether the toxic chemical had been tested near the Queensland town of Innisfail following media reports that it had been trialled there in 1966.
The media reports said that foliage in the area, which is about 100 metres (yards) from the town's water supply, had never properly regrown after the testing.
But the Defence Science and Technology Organisation (DSTO) said Agent Orange had never been used in or near Innisfail.
"DSTO's search of archived reports shows that no trials have been carried out by defence scientists in the Innisfail area using Agent Orange," a defence spokesman said in a statement.
The military conducted "one small-scale defoliation trial" in an area near Innisfail in 1966 to test the performance of herbicides in regular use in the farming and forestry industries, he said.
"Small quantities of commercially available chemicals, Diquat, Tordon and Dimethyl sulfoxide were used," the spokesman said.
"Contrary to media reports, the herbicide 2,4-D -- a component of Agent Orange -- was not used in this trial."
Agent Orange, widely used by US forces in Vietnam to clear jungle cover, contains the extremely toxic chemical dioxin.