A woman was stood on the train between Upminster and Bank at around 4.45pm on December 6 where she was sexually assaulted by a man.
Officers believe the man in the image may have information which could help with their investigation.
Anyone who recognises him is asked to contact British Transport Police by texting 61016 or by calling 0800 40 50 40, quoting reference 540 of 6 December.
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.
A spokesperson for British Transport Police said: “Detectives investigating a sexual assault on board a District line train between Upminster and Bank in December have today released this image in connection.
“At around 4.45pm on Friday 6 December 2024, a woman was stood on the train when a man sexually assaulted her
“Officers would like to speak to the man in the images as they believe he may have information which could help with their investigation.
“Anyone who recognises him is asked to contact British Transport Police by texting 61016 or by calling 0800 40 50 40, quoting reference 540 of 6 December.
“Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.”
