The ABC has apologised for incorrectly reporting that a five-year-old boy had been allegedly raped while on Nauru.
Immigration department secretary Michael Pezzullo debunked the claim during a Senate estimates hearing on Monday attacking media advocacy "parading as journalism".
"There is no five-year-old child, it's a figment," Mr Pezzullo said.
The claims were widely used by refugee advocates, the Greens, the medical profession and sections of the media to argue the case against returning a group of 267 asylum seekers to Nauru following a failed High Court challenge.
The ABC last week said the boy faced the prospect of being returned to the offshore detention centre where his attacker remained but the Human Rights Law Centre has since revealed the boy is not in the group facing deportation.
ABC News apologised for the errors and confusion on Monday afternoon.
The broadcaster said the source, the treating doctor, told the reporter about two cases and the story incorrectly used quotes about an older child in referring to the younger child.
Immigration department official Cheryl-anne Moy told the hearing the child at the centre of the claims was more than twice the age of the younger child.
"The allegation was of a sexual assault from another child who was two years older - it was physical skin-to-skin contact," she said.
"It wasn't an allegation of rape."
The committee heard the boy was now living in the community in NSW and receiving appropriate care.
Australian Greens senator Sarah Hanson-Young, who was part of the chorus deploring the allegation, played down the misreporting.
"The department secretary wants to quibble over how old this child may be," she told reporters in Canberra.
"I think that's a pretty low blow for (those) looking after and looking out for the welfare of a child."
The senator admitted she didn't know the ins and outs of the case but pointed out that there was many cases of children suffering in detention.
Earlier, the immigration department chief took a veiled swipe at state leaders and churches who have offered support to the asylum seekers facing a return to Nauru, saying that "yielding to emotional gestures" reduced the margin of discretionary action the department could exercise.
The group's fate would be considered on a case-by-case basis when medical treatment in Australia was completed.
The Labor premiers of Victoria and South Australia have written to Prime Minister Malcolm Turnbull, offering to help resettle Australian-born asylum seeker children and their families.
Other states including NSW and Queensland have also offered support.
Mr Turnbull said the government had to be careful what signals it sent to people smugglers as it worked through a caseload inherited from the former Labor federal government.
"This is not an easy issue to manage, but it has to managed with a very cool head and a very big heart," he told reporters in Canberra.
Mr Pezzullo said avoiding fanfare and gesture was crucial.
"The moment you have a chink of light, the moment you give someone a clue as to how to game the system, you will put peoples lives in danger."
