A 13-year-old girl was raped after a night out drinking in a trendy bar, police said today.

The girl, who was with a friend of the same age, was found crying in the toilets of the Purple Onion, Middlesbrough, early on Sunday.

She told detectives she left the venue with a man who then raped her in a doorway next to the bar.

She told them she had only had a small amount of one alcopop in the Purple Onion and had not visited any other town centre pubs.

Acting Detective Sergeant Neil Robinson said: ''She was obviously very upset and traumatised when she was initially found.

''We are taking this very seriously indeed due to the fact she is just 13.

''You can appreciate that Middlesbrough town centre is not a place for 13-year-old girls to come into at night.''

The girl, who wore an off-the-shoulder top and high-heeled sandals, looked older than her age, Cleveland Police said.

''No matter what she looks like, she's just 13 and this allegation is something we are avidly investigating,'' Mr Robinson added.

Officers are checking a number of CCTV cameras inside the pub and in the street, and have found images of the girl leaving with a man in a white shirt.

Detectives urged the man, who is white and 6ft tall, to come forward.

Mr Robinson said the venue had co-operated fully with the police inquiry.

He did not want to comment on any action which may be taken against the venue for any potential breach of licensing laws.

The Purple Onion is operated as a restaurant and cellar bar.

Its website claims it is ''frequented by many of the North East's most famous personalities including footballers, musicians and television personalities''.