Police are investigating a video uploaded on Vine which appears to show a woman telling a Tube passenger who is believed to be black: "You have a problem because you guys used to be slaves, yeah".
The altercation took place on the Jubilee Line at Stratford station.
According to Metro, the woman speaks with an eastern European accent and defends herself by saying: "I have black friends, I'm not racist".
A British Transport Police spokesman told the Evening Standard: "We have been made aware of a video posted online which appears to show an altercation onboard a London Underground Jubilee line train.
"Officers are currently analysing the video and are appealing for the person who recorded it to come forward."
In 2013, a commuter who told an Asian man to "f*** off back to your own country" in a vile rant on the London Tube was cleared of racism.
Accountant Claire Moloney was arrested on suspicion of racially aggravated assault after the attack on an unidentified man, which was uploaded on YouTube in November 2010.
The 40-year-old walked free from court after a jury of five men and seven women cleared her of using racially aggravated words to cause harassment.
Moloney sobbed and claimed: "I'm not a racist in any shape or form. I agree the language is horrific and I am mortified.
"I was insulted and I lost it and I ranted; I was arguing my case. I was in a rage, I lost control and I was ranting but he was goading me."
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