A man has been robbed of his wallet and iPhone in Regency Square, Brighton.
The mugger was standing in a doorway as the 26-year-old local victim walked up Cannon Place through Russell Square.
He followed the victim then grabbed him around the throat and threatened him before stealing his wallet and phone.
The suspect made off towards Russell Square.
Detective Sergeant Lex Witek said: “This is a frightening attack for the victim and thankfully he has been left with only a tender throat.
“If you remember seeing someone acting suspiciously at the time or think you recognise the description, please get in touch with police immediately.”
The suspect is described as black, 5ft 11in, aged 23 to 28 years old, very slim, clean shaven, with short cropped black hair and an African accent.
He was wearing a grey hooded top, possibly with a leather jacket over the top and dark trousers.
The robbery happened at about 4.20am on Saturday 25 February.
Anyone with information is asked to contact Sussex Police on 0845 6070999 or call the independent charity Crimestoppers anonymously on 0800 555111.