Search after human birth scene found on Sydney riverbank

A desperate search is under way for a mother and newborn baby after the discovery of a placenta and umbilical cord near a riverbank in suburban Sydney.

Police divers arrived at the Cooks River at Earlwood, about 10km southwest of the city centre, on Tuesday morning as part of a major investigation to track down the unidentified woman and her baby.

Emergency services were called to the site, near a popular riverside walking track, on Monday afternoon after a resident with his dog found evidence of a birth.

Police say tests on the placenta and cord revealed they were from a human, and serious concerns are held for the welfare of both the woman and her child.

Authorities are urging the mother to attend her nearest hospital to receive urgent care.

A large-scale search of the area was conducted overnight and an area near Lang Rd remained taped off on Tuesday.

Investigators were also searching through a grassy area outside the Canterbury Rugby Union Club.

The nearby footbridge over the river is heavily used by local walkers, joggers and cyclists.

The site is less than 4km from Canterbury Hospital.

Superintendent Christine McDonald said lights were brought in to allow the search on Monday night.

"Obviously our search will hopefully identify what has taken place; whether the delivery of that child occurred at this location or another location is yet to be determined," she said.

"It's very important and it's extremely urgent that we find the mother and the child as soon as we can.

"We ask she goes to a hospital. We will be contacting hospitals."

Police did not yet suspect the baby was in the river, Supt McDonald added.

"At this stage our main concern is for the whereabouts of the mother and the child," she said.

"We are doing everything we can and that's why the appeal is to come out, we see that as a really urgent matter for us to find her and her child, hopefully safe and healthy."

The Cooks River flows from Yagoona in Sydney's outer southwest and runs into Botany Bay at Kyeemagh, 23km away.

Sections are heavily polluted as a result of traffic congestion, litter, sewage, illegal dumping and industrial and domestic activities.

A number of Sydney clean-up campaigns have focused on the waterway, while low-lying sections have also been susceptible to flooding.