On Monday at around 1pm (3pm AEDT), tradesmen found the infant inside a drain on La Salle Road in Alexander Heights.

Growing tributes of flowers and toys have been left at the scene since the discovery.

Detective Senior Sergeant Stephen Cleal yesterday said the baby appeared to have been deliberately placed in the drain “in recent days”.

He said the discovery was “very distressing” for the tradespeople and called on the mother to come forward.

”We want to help that mother,” Cleal said.

“We have serious health concerns for that mother.

“Our priority is to get her the medical help that she needs.

“If you are watching, listening, and if you are that mother, please approach the police and let us help you.”

Detectives were making inquiries at medical centers and hospitals – advised to be vigilant – and were reviewing CCTV footage of the locality but remained unsure about the child’s nationality or other identifying information.

Premier Roger Cook described the incident as a “horrifying scenario”.

“The mother of that child must be incredibly distressed,” Cook said.

“Those workers that discovered the child’s body were confronted with the most distressing of circumstances.

“My heart goes out to everyone involved in this horrible, horrible series of events.

“This goes to the heart of everyone’s sense of humanity, a small child whose life has passed under tragic circumstances.”

Anyone with information is urged to contact police immediately on 131 444.