The government's interim immigration cap has left one of the UK's major research universities able to recruit or keep only 78 "skilled" overseas academics this year - and the permanent cap could bring further reductions.
The UK Border Agency has given each university a quota on recruitment from non-European Union countries under Tier 2 of the points-based immigration system, which covers "skilled workers". The quotas cover new visas - and renewals for existing staff - between 19 July 2010 and 31 March 2011, when the permanent cap will be imposed.
University College London, which has more than 4,000 staff, said it had been allowed just 78 places under the interim cap.
Universities are trying to bridge the gap by recruiting under Tier 1, which covers "highly skilled workers". In this category, however, the skills threshold is higher and the number of visas allocated is subject to a monthly national cap.
The UKBA's consultation on the permanent cap, which closed last month, has caused concern among universities by suggesting that Tier 2 visas could be closed to them.
The consultation document notes that there is a "strong case" for granting Tier 2 visas only to migrants with skills that are in "national shortage". This could have disastrous implications for universities because academics are not currently on the National Shortage Occupation List.
Universities UK voiced the sector's concerns in the consultation.
Many institutions believe that the UKBA has failed to appreciate that academic careers are inherently international and that the lengthy training period for new entrants means universities cannot rapidly switch to a "British-only" policy.
The universities of Oxford and Cambridge would not comment on their exact allocations.
But a Cambridge spokeswoman said: "The government's current visa-quota proposals threaten our ability to recruit both the academic leaders of today and the exceptional young talent from which will grow the Nobel prizewinners of tomorrow."