A university union has issued a warning against putting pressure on staff to spy on their foreign students amid fears it would taint the UK's reputation as a place to study.

The University and College Union (UCU) said reports that thousands of students are being reported to immigration officials each year could put future hopefuls from coming to the UK.

Foreign students outside the European Union bring millions of pounds to universities through tuition fees, with some being charged up to eight times more than British undergraduates.

But Damian Green, immigration minister, said the changes were introduced after an extensive consultation.

A UKBA spokesman said: "There has been widespread abuse of the visa system for too long and we have made radical changes in order to make the system more rigorous and accountable.

"We expect education providers who are sponsoring foreign students to make the necessary checks."

Sally Hunt, UCU general secretary, said: "Successive governments have seen plans to turn lecturers into spooks overwhelmingly rejected by the academic community.

"The relationship between staff and students is an incredibly important one that is built on trust. Fears that lecturers are spying on students, whether they are or not, risks jeopardising that relationship.

The union added they would continue to "oppose such moves", which they said would make the UK a less attractive proposition to foreign students.

Academic staff have previously expressed their discomfort at being asked to inform police about Muslim students who are depressed or isolated, after new guidance for countering Islamist radicalism was introduced in August.