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Sally Middleton has not been seen since about 9.30am on Monday at the Werrington Centre where she was due to catch a bus into the city centre.
Officers have released the CCTV image captured at about 10.25am by the escalators in Queensgate Bus Station.
The image shows her carrying a distinctive shopping bag with a tomato soup print.
Chief Inspector Mick Bruce said: "The image clearly shows her appearance and what she was wearing on the day she went missing.
"I would appeal to anyone who saw Mrs Middleton in Peterborough city centre since Monday morning to contact police."
Mrs Middleton is described as being of Oriental appearance, five foot tall and slim.
She has black, greying collar-length hair and brown eyes. She was last seen wearing light-coloured trousers, a light-coloured checked coat and black shoes.
Anyone with any information should call police on 0345 456 456 4.