A South African woman was Thursday convicted of kidnapping a newborn baby and raising her for 17 years before an astonishing coincidence reunited the girl with her biological family.

"You must have been the person who removed the child from hospital," High Court judge John Hlophe told the woman who claimed to have been handed the baby at a train station after entering into a private "adoption" programme.

"Your story if anything is a fairy tale and the court rejects it with the contempt it deserves."