At approximately 4.45pm on Tuesday, a man approached a woman in the store in Malthouse Walk and placed a mobile phone between her legs and took a photo.
He also made physical contact with the woman.
The man then left the shop.
Investigating Officer PC Neil Budd of Banbury police station said: “If you witnessed this offence or have any information please contact police via the non-emergency number 101.
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“We are appealing to anyone in the store at this time, there were a few people seen on CCTV at the time of the offence, we are keen to talk to the man in the CCTV images in relation to this incident.”
Anyone with information should call police on 101 or Crimestoppers anonymously on 0800 555111.