In the clip – which shows a man and woman arguing on a Jubilee Line train in East London – you can clearly hear the woman say to the man “"You have a problem because you guys used to be slaves, yeah,” following a heated discussion.
Her words prompt outrage from the man and other passengers.
She later adds: “I have black friends, I am not racist.”
The footage has been passed on to officers from the British Transport Police who are now appealing for witnesses.
In a statement they added: “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.”