Anti-extremism campaigner and radio presenter Maajid Nawaz has said he was “racially attacked” and hit in the face outside a central London theatre.

In a series of tweets, Nawaz said a white male attacked him from behind outside the Soho Theatre.

He posted a photo of a cut to his forehead and said the man racially abused him and then hit him in the face with “maybe a signet ring”.

The attacker then ran away “like a coward” and “He took nothing. He was just a racist,” Nawaz said.

Nawaz presents a show on LBC radio on Saturday and Sunday lunchtimes.

The Metropolitan Police said they were called to a report of a racially aggravated assault in Dean Street at 7.10pm.

The suspect had fled the scene before officers arrived, no arrests have been made and an investigation has been launched, police said.

Nazaz said: “My forehead will probably be scarred for life. But we will find you, you racist coward, and you will face British justice.”

In one tweet he said there were witnesses who heard the racial abuse, and they gave statements to the police – who “have his face of CCTV”.

Nawaz is the founder of the Quilliam Foundation, a counter-extremism organisation.

He asked not to be contacted, but thanked those who had offered their support.