Police are appealing for witnesses after a video apparently showing a woman hurling racist abuse at a man on the tube was uploaded online.
The footage is believed to have been filmed on an eastbound District line train between Stepney Green and Mile End stations in east London. The time and date of the incident are unclear but a video containing the outburst was uploaded on YouTube on 11 April.
British Transport Police (BTP) released images of a woman they wanted to interview.
DC Lawrence Murphy said: "We have isolated images of a woman we believe may be able to help us with our investigation into the incident.
"We treat all allegations of racism very seriously and urge anyone with information about this incident to contact us."
Anyone with information should contact British Transport Police on 0800 40 50 40 or Crimestoppers on 0800 555 111.
Warning: Video Contains Strong language