Five 14-year-old girls were racially abused and assaulted by two teenagers on a bus in Wembley, the Metropolitan Police have said.
The group were on the route 83 bus at roughly 6.20pm on December 29 when the racially=motivated attack happened.
None of the victims were seriously injured.
The incident was reported later that evening and an investigation was launched.
Police carried out a number of enquiries and have now issued CCTV images of two people they would like to speak to.
PC Matt Cannon, who is leading the investigation, said: "Thankfully incidents of this nature are incredibly rare on the bus network, however we will not tolerate hate crime and we are working to identify these people as soon as possible."
Anyone who recognises the people in the images is asked to call 101 quoting CAD 5443/29Dec or by contacting Crimestoppers anonymously.
