UK universities are popular with overseas students

UK Visas - part of the Foreign Office - says increasing the charge from �36 to �85 is necessary because of growing demand and administration expenses.

But Universities UK, which represents vice-chancellors, said foreign students were being used as "cash cows".

They were estimated to contribute about �10.2bn a year to the national economy and �4bn to higher education.

'Higher costs'

In a letter to Universities UK, UK Visas says applications are "complex to administer" and demands for visas are increasing by 15% a year.

It adds that it "cannot maintain present service levels without significant investments in additional staff, training and equipment".

The letter also says the total cost of a three-year UK degree is more than �30,000. A visa fee increase of �49 represents "only" a 0.3% increase in overall expenses.

Education bodies have until 30 April to respond to the government's plans.

A Universities UK spokeswoman said the timescale was "extraordinary", adding: "Don't they know there's an election on?

"There are no MPs to talk to about this issue, so it is difficult to express our views properly.

"Universities are already finding it hard to attract overseas students, in what is an increasingly competitive market. This will make it worse.

"Some students want to bring their whole family to the UK while they study, which is even more expensive."

She added: "Students get a nice welcome at university but the official welcome from the government is putting them off. We don't want people from overseas to be used as cash cows."

A UK Visas spokesman said that only when the next parliament begins will ministers decide whether to implement the higher fees.

If approved, they are expected to start in July.