Australian military scientists sprayed the toxic defoliant Agent Orange on rainforest in the water catchment area of Innisfail in 1966, local media said on May 18.

The sprayed site, where jungle has never regrown, lies on a ridge about 100m above the Johnstone River, which supplies water for the town in the state's far north.

Queensland state Premier Anna Bligh said she would take the matter to the federal government and urged Innisfail residents to contact the local environmental authority if they had any health concerns.

"Any concerns these residents have can and will be investigated thoroughly just as we have when there's been complaints about unusual cancer rates at workplaces," Bligh was quoted by the media as saying in Brisbane.

"If there has been any suggestion that the defence force has any matters here that they should deal with then I certainly encourage people to talk to the federal government, and we'll be doing the same," she said.

Agent Orange, widely used by US forces in Vietnam to clear jungle cover, contains the extremely toxic chemical dioxin.