Police are looking for a missing newborn baby who they say has been taken from the hospital and desperately needs medical care.

Photo: NZ Police

The two-day-old boy was likely to be with his mother, Dorothy Opetaia, in South Auckland, police said.

Detective Senior Sergeant Malcolm Hassall said police had serious concerns for his wellbeing.

"Police are concerned for the wellbeing of the infant, who was removed from Middlemore Hospital but requires urgent medical assistance."

He asked for Ms Opetaia or any family members to take the baby to any hospital straightaway because delaying medical attention could make him seriously ill.

"I have serious concerns for the wellbeing of the baby boy who desperately requires medical care. Someone in the Opetaia family will know where he is," Detective Hassall said.

Anyone with information was asked to contact the police.