A woman was hit in the face by a man who sexually assaulted her on an Elizabeth line train in east London.
British Transport Police said a suspect sat next the victim and carried out the attack on a service from Stratford to Forest Gate station, Newham.
A spokesman added: “The woman shouted at him to stop, and he hit her in the face.
“Members of the public intervened by pushing the man away, and he left the train at Forest Gate.”
BTP released images of a man seen after the incident on May 16 which is being investigating as a sexual assault.
He is wearing a cream gilet over a black jumper and blue jeans.
The force said: “Officers would like to speak to the man in the images as they believe he may have information which could help their investigation.
“Do you recognise this man?”
Anyone who knows him is asked to contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference 727 of 16 May.
Information can also be given anonymously to Crimestoppers on 0800 555 111.
