Two people were left injured after being attacked on a Metropolitan Line train in north London late at night last month.
Launching an appeal on Tuesday, British Transport Police said the two victims boarded a train at Preston Road station in Wembley when they were attacked by a man at roughly 10.40pm on Saturday, December 9.
The man then ran away from the station before the train departed, police said.
Both victims sustained injuries as a result of the attack.
Officers said they would like to speak to the man in the image as they believe he may have information that could help their investigation.
Anyone with information about this incident is asked to contact BTP by calling 0800 40 50 40 or texting 61016, with reference 825 of 091223.
