A woman was dragged onto Brighton beach and sexually assaulted after leaving a nightclub.

The 18-year-old had left Coalition in King's Road Arches, Brighton, at about 4am on March 12, when she was attacked.

The assault is not being treated as linked to the investigation into the rape of a 17-year-old in Dyke Road Park on February 15, or a sexual assault on a 19-year-old between West Street and King's Road Arches on March 5.

Police investigating the latest attack are trying to trace a passer-by who intervened by shouting, "Hey", and, "What's going on?"

The victim then managed to struggle free and run off.

She has described the offender as being either Arabic or Pakistani, between 20 and 30, between 5ft 5in and 5ft 7in, of proportionate build, with black short hair.

He was wearing a grey coloured V-neck jumper with a white top underneath, dark coloured jeans, rimless glasses and possibly light coloured trainers.

Detective Constable Jon Freeman, from Brighton CID, said: "The victim has only just reported the incident to police as she has tried to put the attack behind her, but this was a serious incident which understandably has left her very upset.

"We would like to hear from anyone who saw what happened or who has information about this assault, particularly the member of the public who shouted out whilst it was taking place, enabling the victim to break free."

Anyone with information is asked to call Sussex Police on 0845 6070999, quoting serial 293 of March March 22, or Crimestoppers anonymously on 0800 555111.