Students in Brighton were today warned of a university rapist after an undergraduate was attacked on campus.

Colleagues at the University of Sussex were put on alert as they were told about the assault, which happened three days ago.

The university is ensuring all students are aware of the attack and is stepping up its regular security patrols.

Police say they believe the rapist, who struck as the 20-year-old undergraduate was walking past Bramber House, Falmer, is an outsider.

He bundled his terrified victim down a flight of steps and threatened to kill her before assaulting her and running away.

The student tried bravely to fight him off, sinking her teeth into his neck and drawing blood before he escaped.

The attack happened between 12.30am and 1.30am on Saturday but police released details only today.

The university was this afternoon urging students to take extra care.

Helen Sloper, 19, who studies geography, said: "I usually walk around the campus by myself. You don't expect this sort of thing to happen. I thought I was quite safe here."

Media student Katie Taylor, 18, said: "I'd not heard anything about it. I live on campus and I've never felt unsafe before."

Neil Chinneck, a 20-year-old media student, said: "Normally I would say I feel quite safe but this would make me worried."

University authorities and the Students Union are helping the police inquiry and the university has handed over CCTV footage from the time of the incident.

Vice-chancellor Prof Alasdair Smith said: "Our first thoughts are with the student herself. The security of our students and staff is of the highest priority, which is why we have an extensive range of measures already in place.

"We hope the CCTV footage we have passed to the police will prove helpful and we would appeal to anyone with information to share it with the police."

There are 11,000 students at the university and 2,000 live on campus.

A spokesman said the university's internal computer system was being updated to warn staff and students of the rape and the Students Union would be issuing safety information.

Student newspaper The Badger would also be appealing for witnesses and providing safety advice.

Officers say the rapist is in his mid-30s and probably not a member of the university.

He is fat and spoke with a northern accent.

He has long dark brown hair, shorter at the front.

He had about two days' growth of stubble and his upper set of teeth are crooked and blackened.

He has bad skin with acne marks on his face and wore a dark, thigh-length trench coat with deep pockets, a black T-shirt, and shoes with rubber soles.

Detective Inspector Graham Pratt said today: "This was a frightening attack. Anyone who recognises this man must call the police immediately.

"We are not focusing inquiries on the student community in isolation. It is more likely the attacker was not a student but we have to keep an open mind."

He urged anyone with information to call police on 0845 6070999 or Crimestoppers in confidence on 0800 555111.