POLICE fear a man who indecently assaulted a teenager in the early hours of last Friday morning had planned a more serious attack.

They say the man was only stopped when the 17-year-old woman, who cannot be named for legal reasons, called to a group of passers by.

The attack took place at 3am on Friday morning as she walked along Shaw Street. As she got close to the bridge over the canal, she was approached from behind by a man.

He pushed her towards some railings and grabbed her around the neck, using his other hand to touch her indecently.

Police say they are particularly worried by the calm way in which he threatened her, warning her not to look at his face, look around or say anything.

Fortunately, she saw a group of young people crossing the bridge and shouted to them.

They immediately responded, and the man then ran off towards the canal towpath.

DS Andy Chambers of Lancaster police said: "I'm convinced that if that group of people had not been there this would have been an even more serious assault. We are very worried about this man."

Police are now particularly keen to trace the group of people who helped the woman.

Two men and two women walked her home, and said they would recognise the attacker if they saw him again, but police have been unable to trace them.

DS Chambers added: "We really need those people to come forward and let us talk to them and find this man."

The attacker is described as white 5ft 11in to 6ft tall (possibly taller), with a local accent, dark hair, clean shaven and he was wearing a dark jumper with thin white stripes.