Detetives are looking for a group of eight or nine young men, aged between 18 and 22, who mocked and attacked a 21-year-old Cambridge student last month for looking like Harry Potter in a scholar's gown. They have released CCTV images of a group of four people in connection with the assault in Corn Exchange Street.

Quinn Coan, who was on an exchange program from Occidental College in Los Angeles, suffered a fractured jaw and a black eye on the night of his 21stbirthday, Nov.1. The American student celebrated his birthday with dinner at Pembroke College with friends and then headed into the city centre while still wearing the traditional university gown.

The politics student and his friends were then approached by the gang for directions to the nightclub Lola Lo.

"We had gone out to get some chips and about eight or nine men stopped us to ask for directions. I was wearing my gown having been at a college dinner to celebrate my 21st birthday. They started to laugh about the gown and made a remark about Harry Potter, Coan said, Mirror reports.

Coan said they suddenly punched him on the right side of his head, stamped on his head and broke his jaw.

"I really think it was because I was wearing a gown. We didn't approach them. It was a totally unprovoked attack. I just want them to be caught," Caon added.

Anyone with information about the assault can contact DS Hine on 101 or Crimestoppers, anonymously on 0800 555 111.

"We are keen to speak to the men pictured as we believe they may have important information which could assist our investigation," Susie Hine, detective sergeant on the investigation team, said in a statement.