Police are searching for the mother of a newborn baby girl whose body was found on a Melbourne beach on Wednesday.

The remains of the baby girl – who still had her umbilical cord and placenta – were found by a passerby on a beach in suburban Seaford, adjacent to the Nepean Highway, about 4.30pm on Wednesday.

Victoria Police said the infant’s body was still undergoing tests to work out when she died, but preliminary estimates were it was within the past three-10 days.

Police hold serious concerns for the health and welfare of the baby’s mother and are asking for her to contact police as soon as possible. Victoria Police said the mother’s wellbeing was their primary focus at this stage.

The exact circumstances surrounding the death and the identity of the infant are yet to be determined.

Anyone with information is asked to contact Crime Stoppers.