Police investigating a serious sexual assault on a teenager have released a 19-year-old man on bail.

He was arrested after the incident in Canterbury in the early hours of Saturday and has been bailed until April 7.

Detectives are still looking for three witnesses.

They particularly want to speak to a couple who helped the victim.

The girl, who is in her late teens, was attacked in an alleyway that leads to Station Road East.

Officers would also like to speak to a man who walked by as the victim spoke to someone near the railway bridge.

Most of the alleyway, near Lansdown Road, and the railway footbridge to Oxford Road, was sealed off on Saturday morning while a forensic investigation took place. It was reopened in the afternoon.

Det Insp Nick Greenan said: "The couple are described as a woman wearing a dark-coloured coat and a man who was either bald, or who had very short hair."

• Contact Canterbury Police on 01227 868118, or CrimeStoppers, free and confidentially, on 0800 555 111.