As soon as the UK Government's aggressive clampdown on immigration began in 2010, there were warnings that the policy could have potentially damaging consequences for Scotland.

In particular, the Scottish Government, university principals and this newspaper warned that the university sector, and the wider economy, could be damaged by the tightening of the rules on student visas.

Four years on from the introduction of the policy, official figures appear to support those warnings. The figures, published today, show that the number of foreign students studying at Scottish universities has fallen since the introduction of the new rules. In some cases the fall has been dramatic. The number of students coming from India, for example, has dropped by almost one-third, and overall there has been a decline in undergraduate and postgraduate students of 4%.

To some extent, the clampdown on visas which has caused this decline was justified. For many years, there were migrants pretending to study at bogus colleges in Scotland while actually working illegally and it was The Herald that first exposed these colleges as a front for immigration.

However, changes to the student registration process have largely dealt with the problem of the bogus colleges and, besides, the tightening of visa rules has more to do with the Tories' ideological opposition to immigration. The problem is that the policy fails to take into account legitimate concerns about its impact in Scotland.

The most serious of these concerns is that reducing immigration will damage Scotland's ability to attract legitimate overseas students and this appears to be happening. What is worrying is that these students pay full fees - in some cases, as much as £17,000 a year - and universities and colleges have come to rely on this income. Indeed, last year overseas students accounted for 12% of the total income of Scottish universities.

At a time of shrinking budgets, Scotland's universities and colleges cannot afford such a threat to their income, but there are consequences for the wider economy too. Not only do the students contribute millions of pounds to the economy while they are here; many stay on and contribute after their course, although most do return home (which is another reason not to target them in a crackdown on immigration).

If there is any good news in today's figures, it is that there has been an increase in students from China, who may not be discouraged by restrictions to post-study work visas in the way students from India appear to be. Had it not been for the Chinese students, the decline in overseas students would have been considerably worse.

If a further decline is to be averted, a review of the short-sighted policy on immigration is needed. With a General Election due next year, and the Tories' focus on the south of England, such a review may be unlikely, but the Government should at least consider an exemption for genuine overseas students in Scotland. These students are here to learn but just as important is the contribution they make socially, culturally and economically.