UK Government proposals for a "crackdown" on international students could prove financially fatal to some universities, MSPs have been warned.

Universities Scotland said higher education institutions in the UK are already at a disadvantage when it comes to attracting students from overseas when compared to their rivals in countries such as America, Canada and Australia.

But director Alastair Sim said further restrictions on where overseas students can study or which courses they can apply for could make the situation worse.

He raised the issue after Home Secretary Amber Rudd revealed plans to overhaul the ''one size fits all'' regime for student immigration, with UK Government ministers considering whether the rules should be tailored to the quality of the course and educational institution.

Mr Sim said Scotland is already "disadvantaged in relation to competitors such as the US, Australia and Canada by not having a competitive post-study work regime" which allows graduates to work for a limited time before returning home.

With MSPs on Holyrood's Economy Committee considering the impact of the UK's decision to leave the European Union, he told them: "A lot of students want to come here, leave India or China or wherever, do their degree, have the opportunity to get some professional experience that follows on from that degree, and then go home and take that combination of academic and professional experience to position themselves extremely competitively in their own workforce.

"Our competitor countries all see the advantage in that and we're at a particular disadvantage.

"What worries me potentially even more is that things look like they might be getting even worse. I'm not quite sure how much is political rhetoric and how much is solid policy proposal, we won't know that for another few weeks yet, but the suggestions in Amber Rudd's speech to the Conservative Party conference that there be a further crackdown on international student numbers and there would be a restriction to only certain institutions or certain courses to recruit international students, that's pretty fatal.

"As the representative of 19 highly quality-assured higher education institutions, I can't understand why there would be a rational for saying to some of Scotland's universities 'sorry you can't have international students'. It would be financially fatal."

Mr Sim said countries such as the US, Canada and Australia have a "much more international student-friendly visa regime" and he added that "students are voting with their feet".

He said: "The number of Indian students in Scottish universities has gone down by 50% since 2010-11. Similarly Nigerian students have gone down 23% since 2010-11.

"So people who can make a choice about whether to come to Britain or go to the United States or go to Canada or Australia are often making a choice they will go somewhere that has a less unwelcoming rhetoric and which has got a better visa offer which enables them to stay on and work for a limited period after their studies."

Earlier, Professor Bradley MacKay, chair in strategic management at St Andrews University, said universities in Scotland are "hugely reliant" on EU funding, staff and students, meaning a so-called soft Brexit would be best as immigration is "fundamental" for the Scottish economy.

He told the committee: "Given the configuration of the Scottish economy to the British economy, a soft Brexit - something that kept access to the single market - would certainly be desirable.

"Particularly for the Scottish economy immigration is absolutely fundamental as well. A range of different industries in Scotland are really very reliant on having skilled immigration and in some cases non-skilled as well.

"Financial services, for example, relies on being able to fairly easily recruit top talent,