This shocking video shows a woman hurling racist abuse on a train - before squaring up to a passenger who challenges her behaviour.
Police have confirmed they are investigating the incident, which took place near West Ham underground station in east London on Friday night.
Clips of the confrontation have been posted on social media, where commenters have slammed the woman's actions.
The footage opens with the woman - dressed in a purple and white outfit - calling an unidentified man a "f****** Algerian c***".
She then continues the torrent of bile, hurling racial slurs and insulting his weight - before threatening to knock him out.
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Another woman also appears to become involved in the incident, which is being filmed from further down the carriage.
The video then cuts to the first woman moving towards the camera and challenging the man who is recording the encounter.
She says: "Carry on recording me because I don't care - I'll f*** all of yous [sic] up."
The pair then continue arguing - before the woman threatens to stab the man in the face.
She says: "I'll stab you in the face. You don't understand, look - I've been shanked in the face."
The clip has been posted on a popular Facebook account, where more than 300 people have left comments.
One said: "What an absolute embarrassment."
Another added: "Hope she feels shame, name and shame that's what I would do."
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Others also praised the man holding the camera for staying calm in the face of the aggression.
British Transport Police confirmed to the Mirror that the spat had been reported.
Officers are now appealing for information.
A statement said: "British Transport Police received a report of a racially aggravated public order offence on-board a train near West Ham Underground station at 11.31pm on Friday 16 July.
"Officers are aware of footage on social media of this incident, and enquiries into it remain ongoing.
"Anyone with information is asked to contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 749 of 16/07/21."
The Mirror has also tried to contact the man believed to have filmed the footage.
