Just before 9.30pm on Sunday 20 September, a woman was stood on the platform at Langdon Park DLR station as a train approached.
As the victim alighted the train, the woman ran down the platform and hit him.
The woman is then reported to have pulled out a large knife concealed within her clothing and lunge at the victim with it.
The pair then wrestled for control of the knife which resulted in the weapon falling on the floor before the victim picked it up and ran out of the station as the woman chased him.
If you recognise her or have any information, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 2000064928.
Alternatively, you can call Crimestoppers anonymously on 0800 555 111.