A black passenger filmed a white man doing a monkey impression aimed at him on the London Underground’s Northern Line last week.
The man swung from seat to seat and approached the passenger, Mohammed Dirir, while other commuters looked on.
Dirir posted the video on Instagram with a comment that read: “Racism is still alive, to all my people of colour around the world stay strong!” The post has since been deleted.
British Transport Police were treating the incident as “racial abuse” and issued a call for witnesses on Monday.
The incident sparked outrage on social media. Twitter users called the episode “shocking,” “disgusting” and “disgraceful,” often criticizing the passengers for remaining silent.