Australia's top immigration official has said allegations a five-year-old boy was raped in the migrant detention centre in Nauru are "a figment".
Department of Immigration and Border Protection secretary Michael Pezzullo criticised media coverage of the case as "advocacy parading as journalism".
The Australian Broadcasting Corp has apologised for a reporting error.
The case was widely reported last week as the High Court ruled Australia's offshore asylum policy was legal.
The ruling meant more than 260 asylum seekers in Australia - including dozens of children - were expected to be deported imminently to Nauru.
There was widespread anger among activists at the prospect of the boy being returned, but Mr Pezzullo said on Monday there was "no five-year-old child, it's a figment".
The ABC has issued an apology, saying it misreported comments made by a paediatrician on two separate cases.
The doctor had referred to one case involving a five-year-old who was allegedly sexually assaulted and another about a 10-year-old who was allegedly raped in Nauru.
The ABC said its story "incorrectly used quotes about the older child in referring to the younger child".
Paediatrician Karen Zwi said the information she had given the ABC was "factually accurate".
"A child is a child. I stand by the statements I have made with regard to children in detention," she said.
The Human Rights Law Centre has also confirmed the younger boy was not among the children linked to the High Court ruling.
All immigrants trying to reach Australia illegally by boat are detained. They are taken to Nauru and Papua New Guinea for processing, with those found to be genuine refugees resettled in Papua New Guinea, Cambodia or Nauru itself.
The government says the policy deters people smuggling and stops people dying at sea
But critics say Australia is ignoring its international obligations, and there are repeated allegations of abuses and poor conditions in the camps.