The abandonment of a newborn baby in a drain in Sydney has sparked renewed calls for the introduction of baby hatches in Australia.

The boy, believed to be two or three days old, was discovered on the side of a bike track along the M7 motorway at Quakers Hill on Sunday morning after a passing group of cyclists heard cries.

Police believe the baby was squeezed through the drain’s narrow opening and dropped about 2.5 metres. He was still wrapped in a striped hospital blanket, with his umbilical cord cut and pegged.

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“It was disturbing (to see) how the child was placed in the drain,” Quakers Hill duty officer Inspector David Lagats said.

“We all thought the worst but the baby was still alive.”

Investigators frantically cross-checked hospital records and doorknocked the homes of patients before eventually identifying the 30-year-old mother.

She is being questioned at Blacktown Police Station.

Police believe the baby may have been in the drain since last Tuesday.

Labor senator Helen Polley said the idea of emergency hatches – where parents can safely place unwanted babies – warrants further investigation and has called for safe havens across the country in places such as fire stations, police stations and hospitals.

Germany, Japan and Italy are among countries that have baby hatches.

Baby abandonment is currently treated as a criminal offence in Australia, with parents liable for prosecution.

“Here, a parent could legally abandon a baby without fear of criminal prosecution,” Ms Polley said.

“Let’s make sure mothers and babies are provided [with] … the compassion of a modern society.”

Inspector Lagats said there were no signs of physical injury but the baby was malnourished.

He remains in a serious but stable condition at Westmead Children’s Hospital.

Police doubt the baby would have survived as temperatures in Sydney’s north west reached almost 40 degrees on Sunday.

“It was already undernourished, and dehydration would have taken affect so we would have had grave fears for the child’s welfare had it been exposed to this weather for the rest of the day,” Insp Lagats said.

Officers are following up reports of a man of Indian appearance in an orange shirt seen on the track at about the same time the baby had been discovered.

The baby is now in the care of the NSW Family and Community Services (FACS) Minister.

It will be up to the state agency to assess how – or if – the mother and baby can be reunited.

FACS western Sydney director Lisa Charet said often with abandonments, people were in a place of depression.

“There’s been cases where mothers have had post-natal depression, or those sorts of issues, or they’re very young and they don’t know where to go to for help,” she said.

– with AAP