TOUGH new rules on international students coming to the UK could be hitting the economy.

That's according to Newport University's acting vice-chancellor Stephen Hagen who signed a letter to the prime minster with 21 other university vice-chancellors over the issue.

Overseas students are not permanent migrants, the letter says, with vice-chancellors calling for students numbers to be taken out of net migration figures,.

According to the letter the tone of recent reforms has hit the market for overseas students and damaging it will have a "detrimental economic, political and cultural impact at a time when we should be encouraging... areas of strength and growth."

"When they return home, international students act as ambassadors for the UK," the letter reads.

"The majority do, in fact, return home on completion of their studies or after a short period of postgraduate employment.

These are not permanent migrants; they come to the UK for a limited time providing vital economic and cultural stimulus while they are here and beyond.."

The vice-chancellors, whose universities are all members of the University Alliance, argued that there was a compelling case not to use reductions in international student numbers as a means of meeting net migration targets and to encourage them to come to Britain by making two-year post study work visa more easily available.

That would be in line with competitors such as Australia and Candada, the letter said.

"We need to send a strong message around the globe to say that the UK is open to any legitimate international students," said Libby Hackett, chief executive of the University Alliance.