Police are hunting a man who screamed racist abuse at three women on a Northern line train.
It happened at about 8.50pm on November 16.
The victims have not contacted the police, and officers have urged them to get in touch.
A British Transport Police spokesman said: “Since this incident was reported, the victims have not yet contacted police.
“Officers are today appealing directly to those victims, and would urge them to contact police as soon as possible.”
Anyone with information is asked to call British Transport Police on 0800 40 50 40, quoting reference 757 of November 16, 2018. Alternatively, call Crimestoppers anonymously on 0800 555 111.