A woman was sexually assaulted as she was travelling northbound from Oxford Circus to Highbury and Islington at around 6.30pm on October 23.
The British Transport Police released a picture of a man they believe may be able to help with the investigation.
Anyone who recognises him is asked to contact BTP by texting 61016 or by calling 0800 40 50 40, quoting reference 529 of 23 October.
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 Victoria Line train have today released these images in connection.
“At around 6.30pm on Wednesday 23 October, a woman was sexually assaulted by a man on board a northbound Victoria line train from Oxford Circus to Highbury and Islington.
“Officers believe the man in the images may have information which could help with their investigation.”
