Authorities in Sydney are urgently searching for a mother and newborn baby.

A resident discovered a human placenta and umbilical cord on a riverbank in Earlwood.

Police have confirmed the organs are human, raising serious welfare concerns for the missing pair.

Superintendent Christine McDonald emphasized the importance of finding the mother and child promptly due to environmental factors of the polluted Cooks River.

The public is urged to provide any information or CCTV footage to aid in the search.

Authorities are encouraging the mother to seek urgent medical assistance at the nearest hospital.

The river's flow from Yagoona to Botany Bay adds to the urgency of locating the mother and baby as soon as possible.