Police believe the attacks, which happened in the West End in January, could be linked.

Students are now being urged by university authorities to take extra care over personal safety.

The university's social services director Judith Carey said they felt such action was appropriate.

Personal alarms

She said: "Obviously there have been a very limited number of concerns that students have raised over the years that the university's dealt with.

"But they have tended to be on a one-to-one basis where it's been an individual issue for an individual student and we've supported them through that."

Female students are being urged to walk home in groups after dark and to generally look out for each other.