WA Police are following up fresh leads in their search for the mother of a baby boy found dead in a stormwater drain.

The heartbreaking discovery was made by tradies carrying out routine maintenance work in Perth’s north about 1pm on Monday.

Police believe the child was wrapped in a sheet and placed in the drain on La Salle Rd in Alexander Heights in the days before he was found, and are now searching for his mother.

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“It’s an unimaginable situation that we have to think about,” WA Police Commissioner Col Blanch said on Wednesday.

“Our thoughts go out to the mother. Not only are there concerns about the mother’s health, but also mental health and family surrounding the mother.

“I think help is the first thing we all think of in this situation, as tragic as it is for that baby boy.

“The easiest way to bring this to a resolution is for the mother or the family to come forward and let us know what has happened.”

Hospitals have been put on alert that she may need urgent care.

Police have fielded plenty of calls from people who believe they have seen something that could help.

“We’ve got some leads,” said Blanch.

“The job now is to sift through which ones may be relevant and which ones may not.

“(Homicide squad detectives) will follow everything down.

“So my message continues to be to our community, even if it doesn’t seem relevant, if you’re in the area, just ring up Crime Stoppers and tell us what you saw.”

Physical and forensic testing has been completed over the last 48 hours, with the analysis of that “still ongoing at this stage”.

Authorities have been down the stormwater drain to collect information.

Detective Senior Sergeant Stephen Cleal said on Tuesday that it was a “highly distressing and confronting situation”.

“(The tradies) were clearing the drains in the area of any debris or checking for blockages. It was routine work,” he said.

“There was no information that sent workers to that drain. This was a chance discovery.

“They were very unprepared. Not that you can prepare for a discovery like this, but they were very unprepared.”

Floral tributes and toys have been left at the scene where the boy was found.

Anyone with information should contact Crime Stoppers.