University lecturers are in danger of being attacked, intimidated or harassed by students, research claims.
A study for the Nuffield Foundation details cases where academics have been attacked, stalked or sexually harassed by students.
A union representing university lecturers, Natfhe, says the problem is a growing one - and one which universities are failing to deal with.
It says the increase in the problem is due in part to the growing pressure students are under.
The study for the Nuffield Foundation was carried out by Deborah Lee, of Derby University.
It includes reports on incidents in which lecturers have been attacked. One student threatened to stab a lecturer.
Bullying
Writing in the Times Higher Education Supplement (THES), Deborah Lee said: "Academics have been physically assaulted in classrooms, stalked around campus, sexually harassed via e-mail, verbally threatened at home and maliciously accused of poor teaching".
The research involved interviews with 20 academics who came forward in response to an appeal for victims of student bullying in the THES newspaper.
Natfhe union official Andy Pike says he is not surprised by the study's findings.
"There have been more complaints made against university professionals and an increase in bullying and harassment," he said.
Poor marks
He says students are under a lot of pressure.
"A lot is riding on the results in terms of investment and what it means in terms of increased earning potential.
Mr Pike said problems often arose when students disagreed with low marks awarded for their work.
This might lead to complaints against the academic which went beyond their marking.
Natfhe says universities have a good system in place for dealing with students who have complaints against staff, but nothing to protect staff.
"We feel it's a one-way street," he said.