An air search found the child, Danielle Lane, in rough terrain about 13 kilometres from the Tjirrkali Aboriginal Community, 180 kilometres north-west of Warburton, about 2pm yesterday.

It has been claimed she was taken by child sex offender Augustine Winter Miller, 38 from a remote Aboriginal community on New Year's Eve.

Temperatures in the area had soared close to 40 degrees this week and the severely dehydrated child had fallen unconscious after police found her.

Rescuers took the pair back to the Tjirrkali community for medical treatment but the child's "seriously unwell" condition worsened, police spokeswoman Susan Usher said.

Ms Usher said police commenced CPR for a "lengthy time" before medical staff flown in from Warburton took over.

Danielle did not recover and police are treating her death as suspicious.

Mr Miller, reportedly convicted of child sex offences in January 2006, spent the night in police custody but no charges have been laid yet.

Police have previously said that Mr Miller is the de facto partner of the young girl's mother, who is believed to be suffering terminal cancer.

- with Aja Styles