Dozens of people stopped traffic in Birmingham to protest after an alleged assault on a teenage girl in a shop.
Black community leaders said the girl had felt unable to approach the police because she was an illegal immigrant and was worried about being deported.
They said she was assaulted in a shop in Perry Barr during the weekend.
West Midlands Police said any approach to officers would be treated sensitively and in confidence.
Supt Tom Coughlan said: "It is important if any assault took place which has not yet been reported, police are informed at the earliest opportunity so a full investigation can take place."
Police would not comment on how many people were involved in the protest but a BBC correspondent at the scene said numbers reached 150.