Two people were assaulted at Shoreditch High Street station - with one of them left with three broken teeth.
At 7pm on April 22 a man pushed by two people on a stairwell at the station.
When he reached the top of the stairs, he turned around and punched both - one in the face and one in the neck.
READ MORE: Chadwell Heath boy, 12, sentenced for robbery spree
According to British Transport Police (BTP), one suffered three broken teeth and a cut above her lip that required stitches.
The second assault victim did not sustain any injuries.
READ MORE: Met Police officer 'offered to supply cocaine and MDMA'
A BTP spokesperson said: "The man is described as white, in his late twenties or early thirties with dirty blonde hair and a skinny build.
"On the evening of the incident he was wearing a black hoody and black jogging bottoms, both covered in white paint."
For the latest crime news in east London, join our East London Crime Watch group on Facebook.
Officers are keen to speak to anyone who was at the station that evening, or anyone with information that may assist the investigation.
Witnesses are asked to contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 890 of 22 April.
Alternatively, call Crimestoppers anonymously on 0800 555 111.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here