Newborn found dead on beach had umbilical cord attached

A dead newborn, left on a Melbourne beach with her placenta and umbilical cord, may have been there for two days before she was found.

Police believe the baby girl was left on Seaford Beach between 7am and 5pm on Monday.

Investigators are appealing for the girl's mother to get in touch as they hold serious concerns for her health and welfare.

A passer-by found the infant's remains on the beach adjacent to Nepean Highway about 4.30pm on Wednesday.