Home Office plans to nearly double visa extension charges for international students came under fire this week from vice-chancellors, college heads and student leaders.
Despite widespread protests against the proposals, which were published in a consultation paper last September, the Home Office is preparing to raise the charges in April from £250 for a "premium service" to nearly £500 in some cases.
The rises will affect international students who wish to extend their period of study in the UK. This would include, for example, those progressing to postgraduate study.
Universities UK has written to Tony Blair, Charles Clarke, the Home Secretary, and Ruth Kelly, the Education Secretary.
It warns them that the increase in visa extension charges could seriously damage the ability of universities and colleges to attract and retain full fee-paying international students in the face of growing competition from overseas institutions.
Ivor Crewe, president of UUK, described the charges as "grossly excessive" and "very unfair".
He added: "I have no doubt whatsoever that this will make it much more difficult to persuade international students to come to this country."
Baroness Warwick, UUK's chief executive, said that the higher charges could have a particularly severe impact on science, technology and engineering courses because of the high proportion of international students in these disciplines.
She told Mr Blair that this could further weaken vulnerable departments.
On Monday, UUK joined the Association of Colleges, Ukcosa: The Council for International Education, the British Accreditation Council and English UK (the English-language colleges group) in emergency talks with officials from the Department for Education and Skills.
Dominic Scott, Ukcosa's chief executive, said: "What is being proposed is out of proportion to what anyone thought was their worst nightmare."
The National Union of Students has also written to Mr Clarke expressing "extreme concern" over the plans.
The Home Office has said that the higher charges are necessary to save UK taxpayers the costs associated with processing visa extensions, which amount to about £100 million a year.