The incident occurred at Mile End Underground station between 9am and 9.45am on May 1, when a woman was followed off a District line train by a man.
The woman, in her early 20s, stood on the platform waiting for an east bound service.
Despite the platform not being busy, the same man stood “extremely close” to her before allegedly sexually assaulting her.
Police believe the man pictured could help their investigation (Image: British Transport Police) According to the British Transport Police (BTP), he then followed the woman onto a bench at the station before following her onto a train whilst staring at her.
At South Woodford, the woman was again followed off the train but she managed to escape him by jumping back onto the train as the doors closed.
READ MORE: Man in hospital after assault at underground station in Mile End
BTP have shared an image of a man they believe may have more information that could help the investigation.
Anyone who recognises them is asked to contact BTP by texting 61016, or by calling 0800 40 50 40 quoting reference 394 of 1 May.
Information can also be given anonymously to Crimestoppers on 0800 555 111.