A woman aged 20 was sexually assaulted in the Hanover area of Brighton in the early hours of Sunday morning.
A stocky, blond-haired man with a pox-scarred left cheek attacked the woman in Newhaven Street.
He pushed her up against a wall, before grabbing her chest and sexually assaulting her.
The man then ran off to the south, towards Albion Hill, after the victim pushed him away and yelled out.
The attack happened between 3am and 3.45am on Sunday (14 November) and left the victim, who lives in Brighton, feeling shaken.
Detective Constable Melanie Wauchope said: “The victim has understandably been left very shaken and we are doing everything we can to support her.
“The victim, from Brighton, walked from the Easy Hours 24 hours shop near the Old Steine, before walking along Newhaven Street.
“I am keen to speak to anyone who was in the area at the time of the assault and saw anything suspicious.
“The man has bright blue eyes, chicken pox scars on his left cheek, short shaved blonde hair and is of stocky build.”
She said that he was white, around 25 years old, 5ft 7in tall and was wearing a black Superdry waterproof jacket and blue jeans.
Detective Constable Melanie Wauchope added: “If you think you may recognise this description, please contact us immediately.”
Anyone with information is asked to contact Sussex Police on 0845 6070999 or the independent charity Crimestoppers anonymously on 0800 555111.
