The new immigration cap that came into force this week may deter leading international academics from joining UK universities, according to the sector's representative body.
On 6 April, the government introduced its cap on the number of skilled migrants who can enter the UK from outside the European Union; this is set at 20,700 for the year for those entering on Tier 2 of the points-based immigration system.
The cap, which was implemented on an interim basis last year, was a Conservative Party manifesto pledge for last year's general election.
Universities wanting to recruit from overseas will have to fight it out with other sectors - including big international recruiters in fields such as financial services and IT - to be granted certificates of sponsorship, allocated on a monthly basis.
After pressure from Universities UK and the sector, the government changed its original plans and has now awarded an extra 20 points for "PhD-level" jobs.
A UUK spokesman said that while the full impact of the new system would not be apparent for several months, "there are concerns that the ability of universities to recruit talented non-EU academics may be compromised".
He added: "The prioritisation of scientists and researchers under the new system is welcome, but this is no guarantee that they will be successful in obtaining visas. This is very much dependent on the volume and type of applications made to Tier 2 in a given month."
There are also concerns about the length of the application process.
The university must apply for a certificate of sponsorship (which UUK said would take four weeks), and only after it is awarded can the overseas academic apply for a visa.
"Top-class academics and researchers are likely to be in demand globally. Delays such as these may lead to some individuals going elsewhere," the UUK spokesman said.
Elaine McIlroy, senior associate at immigration law experts Dundas & Wilson LLP, said that the extra points for doctoral-level jobs "may be a saving grace for some universities".
She added: "The result of this is that a scientific researcher, for example, with a salary of £23,000 a year would be on an equal footing with an employee in a non 'PhD-level' job with a salary of £74,000."
Pressure from universities and scientists also helped to spur the government into creating a category for "exceptional talent", which will provide an extra 1,000 places a year.
However, this category is not ready for implementation, and Ms McIlroy said it would be quite difficult to meet its requirements.
"It is not a replacement for Tier 1," she said, referring to the old category for the highest-skilled migrants scrapped under the new system.
You mean there are rich guys too? Business schools representative says student-visa policymakers have 'no idea'
Overseas applications to UK business schools have been hit hard by the tightening of student-visa rules, the head of the Association of MBAs has said.
Sharon Bamford, its new chief executive, told Times Higher Education that schools were reporting a steep fall in acceptance rates compared with last year, and pledged to continue to lobby the government over reassessing its position.
Highlighting the potential impact on the UK economy, she said: "The most alarming thing is how ill-informed the government was.
"When we met the (people) making these decisions, they had no idea of the MBA costs at London Business School and therefore the income generated by that."
She added that they could not distinguish between a "16-year-old at an unaccredited language college and a 30-year-old businessperson ... coming here to do an MBA".
Ms Bamford said ministers had failed to learn the lessons of the Thatcher government, which raised postgraduate tuition fees and gave international students a reason to choose the US academy over the UK's. "With those students, their children are now going to the US. The effects are longer term than we may first imagine."
The challenges facing business schools were also addressed at a roundtable event in London last week. Thierry Grange, dean and director of the Grenoble School of Management, said it was necessary for business schools to rethink the material they teach.
"Today we no longer need to spend time on marketing and finance. You can learn that by distance learning on the web," he said. "Globalisation means that we have to give more geopolitical knowledge to the students; more philosophy, more cultural background."
However, Bob O'Keefe, former dean of the Faculty of Management and Law at the University of Surrey, said accreditation rules tied schools to teaching basic principles.
Ms Bamford said she may review the association's accreditation rules to encourage fresh approaches. "I am asking the question: 'Does the accreditation system inhibit innovation?'"