Police believe a nine-month-old girl found dead on an Australian beach was thrown into the water as a "sacrifice", it has been reported.

Her naked body was found on Monday in Surfers Paradise, Queensland, and is believed to have drifted for two days.

A family of four were tracked on CCTV travelling to the Jack Evans Boat Harbour in New South Wales on Saturday, according to the Australian Associated Press (AAP).

It is alleged this is where the baby was thrown into the water - with an empty pram left on the waterside - before the family returned to Queensland by bus.

The family were said to have been living rough.


The AAP quoted police sources as alleging the child's 23-year-old mother had admitted knowing about a planned "sacrifice", but that only the father would be accused of throwing her into the water.

The mother has reportedly been released from custody and placed in mental health care.

New South Wales Police secured the extradition of a 48-year-old man from Queensland as part of their investigation, after establishing the baby had died in the state.

A court was told the accused has schizophrenia and is of limited education.

"It is anticipated he will return to NSW where he will be charged with a warrant," the force said in a statement.

Police divers are currently searching for clues in the area around the harbour and nearby Tweed River.

"Clearly the child was located in the water up at Surfers Paradise," NSW Police detective chief inspector Wayne Walpole told reporters.

"We want to know how the child got there. We are looking for evidence that could assist us."