A 30-year-old woman who had been missing in an Australian rainforest for more than two weeks has been found alive.

Shannon Fraser went missing on September 21 near the remote Josephine Falls in Queensland state after becoming disorientated, wearing just leggings, a shirt and flip flops, the AFP news agency reported.

Fraser was spotted by a banana farmer on Wednesday, covered in cuts, welts, bruises and insect bites, Brisbane's Courier-Mail reported.

"She's lost lots of weight, she's covered in cuts and scratches, but she's in good spirits," her brother Dylan Fraser told the newspaper.

Reports said she has lost nearly 17 kilogrammes during her ordeal, surviving a chase by a crocodile and eating small fish for food.

Police said they were surprised that their search for the mother of three had failed to find her.

"Can I say the methodologies that are employed in that search operation are tried and proven and extremely sound," Inspector Rhys Newton told journalists.

"I am convinced that there was an extremely high probability of locating that missing person had she been in that area that we were searching."

Shannon's brother Dylan told national radio: "She just stayed strong, and made it out."

Her partner Heath Cassady, who reported her missing and helped in the search effort, said he was overjoyed that she was back safely.

"Her whole body is scarred and peeling, she's been through a lot," he said. "It is amazing she's still alive."