Audrey Nyanor was allowed to leave police station with woman who claimed to be family friend.
The police watchdog has been called after an 18-month-old girl was taken from a London police station by a mystery woman, a Metropolitan police spokesman said today.
The force voluntarily referred the case to the Independent Police Complaints Commission (IPCC), he said. The girl, Audrey Nyanor, who is of Ghanaian heritage, is still missing.
Scotland Yard released CCTV footage of the woman who turned up at Walworth police station in south-east London saying she was a friend of the toddler's mother. Audrey was last seen wearing pink trousers, a pink coat, and a multi-coloured pink and white hat.
The Met said the child went missing after officers went to an address in De Laune Street, Walworth, south London, on Thursday to make inquiries about a man wanted for failing to appear at court. He was not at home, but police arrested the girl's 36-year-old mother in connection with alleged immigration offences.
The mother and child were taken to Walworth police station, where officers spoke to family members and friends to arrange for Audrey to be looked after.
The spokesman said: "At approximately 10.30am a woman attended the police station purporting to be a 46-year-old friend of the mother. The details she gave to police corresponded with the name of the woman Audrey's mother had told police would pick up her daughter, and as a result she left the police station with the child at approximately 10.40am.
"Subsequently it became apparent that the woman was not the same person who had been organised to pick up the child. As a result a police investigation began to find Audrey, and to identify and trace the woman who took her. Whilst there is no evidence at this stage to suggest that Audrey has come to any harm we are very concerned that she remains missing and we are making every effort to ensure she is safely returned."
Police issued images of the woman at the police station and at Elephant and Castle underground station, where she was pictured carrying Audrey. Audrey is believed to be of Ghanaian heritage, of medium build and has short black hair. She was wearing a bright red coat and dark knee-length boots.
Audrey's mother was later released on bail. Five other people been arrested in connection with the investigation have also been bailed, according to the Met.
Anyone with information should call the incident room on 020 8721 4906 or Crimestoppers on 0800 555 111.