Civil engineering at the University of Westminster is to cease because of a drop in applicants, it was confirmed this week.
Students have received letters telling them that those who have not completed their studies by the end of the year will be transferred to South Bank University. About 60 undergraduate and postgraduate students are affected.
Some of the five-and-a-half staff posts are also likely to move to South Bank, although redundancies are possible. Talks with staff will take place in coming weeks.
The university will also have to decide what to do with the unique construction hall site on the Marylebone Road, originally built exclusively for engineering.
It is unlikely to be sold but could be used to relieve overcrowding in other departments.
Trish Richards, welfare and education officer at the student union, said the union was taking legal advice on whether Westminster had failed to honour its contract with students studying civil engineering.
"When they decided on Westminster, there were a number of factors that helped them in that decision, such as geography, course structure and teaching contact," she said. "My fear is that all this change will be to the detriment of their studies."
Alan Jago, head of the school of the built environment, said although the University of Westminster had made arrangements directly with South Bank, students could go elsewhere if they wished to make their own plans.
Decisions would be made about the civil engineering site "sometime this academic year", he said.
A university spokesman at Queen Mary and Westfield College, which is also closing its department, said decisions about a potential five redundancies had been postponed until early February.
Meanwhile, City University and University College London both report good numbers of student applications.
Roger Wootton, dean of engineering at City University, said that while the university would not approach students from departments that were closing, it would look at any students who expressed an interest.