The Government's approach to immigration will deter outstanding scientists from coming to work in the UK in the wake of Brexit, the Astronomer Royal has said.
Lord Rees branded a speech by Amber Rudd to the Conservative conference in Birmingham "deplorable" after the Home Secretary announced businesses and universities would face new restrictions on recruiting overseas workers and students.
The former president of the Royal Society told BBC2's Newsnight that the approach could put off scientists like British Nobel Prize winning physicists David Thouless, Duncan Haldane and Michael Kosterlitz from working in the country.
Lord Rees said: "Let's recall that these three people went to the US in the early 1980s, the Thatcher period when science was doing very badly and many people defected in that time.
"In the last 20 years, UK science has greatly strengthened because it has become far more international and far more involved with mainland Europe. It would be very sad if this was jeopardised by limiting immigration and the difficulty of collaborating with Europeans. So let's hope that doesn't happen.
"I thought Amber Rudd's speech was really deplorable because that would certainly lead to difficulties. The perception is worse than the reality. People will feel like they are not welcome and they won't apply to come and they won't take jobs here."
He added: "In the last 10 or 20 years the gradient was positive but all that could be lost by the perception of what is happening now.
"Two things will happen. First, outstanding foreigners won't want to come and work here. People who are working here will feel that they do better abroad and, of course young people will feel that science is not a career where they can do the best work in this country and they won't go into science."