More than 2,300 EU academics have resigned from British universities over the past year amid concerns over a “Brexodus” of top talent in higher education.

New figures show a 19 per cent increase in departures of European staff from universities last year compared to before the EU referendum, and a 10 per cent rise from some 2130 resignations in 2015-16.

Theresa May has urged EU citizens to stay in the UK after Britain leaves the bloc but prolonged uncertainty over post-Brexit rights has made some academics fearful for the future, critics warn.

It comes after a report from the British Academy warned that the UK’s world-leading university sector could be under threat due to prospective changes to immigration rules after Brexit, with subjects such as modern languages and economics facing the greatest threat.

The institution reporting the highest number of resignations was the University of Oxford, which saw 230 departures of EU academics last year compared to 171 in 2014-15, according to freedom of information requests by the Liberal Democrats to 105 universities.

However the university pointed out that it has also recruited a large number of EU staff so the overall numbers were largely similar.

A spokesman said: “The status of colleagues from other parts of the EU has been a major concern for the university and we have called for clear commitments on this issue to reassure staff and students who are already here or hoping to join us.

“The recent joint report on Brexit negotiations confirmed the rights of academics and other staff currently in the UK but the university will continue to call for a free flow of academic talent to and from the EU in the final Brexit settlement.”

King’s College London also lost 139 members of EU staff, compared to 108 before the referendum, while 173 EU academics resigned from the University of Cambridge last year, up from 153 staff the previous year, and 141 in 2014-15.

The institutions that responded reported more than 25,400 European academics on their rolls, with 6,633 working on Stem subjects such as engineering, maths and computing, where the UK faces serious skills shortages.

Another 4,922 work on vital areas such as health sciences, nursing or medicine, and 1,307 on business.

Maike Bohn, a spokesperson for the3million, which campaigns for citizens’ rights, said some EU academics feel “personally insulted” by the Government’s sluggishness to guarantee their rights and remain concerned about what Brexit will mean for their futures.

Ms Bohn, a German citizen who formerly worked at Bristol University and the Saïd Business School in Oxford, told The Independent: “I think we will see a time lag on this as I know lots of people who are waiting to see if it gets worse before leaving.

“It takes time to get a new position in Europe so I think we will see a delayed reaction.”

Younger academics are worried about whether their qualifications will still be valid after Brexit, while others are concerned over their eligibility for lucrative European research grants once Britain leaves the bloc, she said.

Liberal Democrat education spokeswoman Layla Moran said: “This alarming rise in EU academics leaving our universities is the latest sign of a damaging Brexodus.

“Britain’s universities have thrived from having access to talented European researchers, and from years of European cooperation through schemes like Horizon 2020 and Erasmus.

“Now all this is being put at risk by this Government’s botched handling of Brexit, where we seem to be losing all the benefits of EU membership while keeping the costs.

“These valued members of our communities find themselves uncertain about the future and unconvinced by the too little too late wooing by an incompetent Prime Minister. While they were frozen out of the referendum, they are now voting with their feet.”

The Prime Minister secured a deal with Brussels before Christmas that would allow EU citizens who arrive by March 2019 to apply for settled status if they have been living in the UK for more than five years.

Anyone who has lived in the country for less than five years before the official exit date will be able to apply to remain until they have reached the five-year threshold.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

The move has been welcomed by some although it also raised further uncertainty about who will qualify for lesser rights after Brexit.

Alistair Jarvis, chief executive of Universities UK, which represents higher education institutions, said the agreement on the first phase of Brexit talks had offered “much-needed certainty” for the 46,000 EU nationals working in UK universities, as well as the promise that membership of European programmes such as Erasmus would continue.

He added: “The Government now needs to develop a post-exit immigration system that welcomes European and international university staff and students with minimal barriers.”

A Department for Education spokesperson said: “The UK higher education sector has a long established tradition of attracting the brightest minds from around the world, at all stages of their careers. We value the contribution that EU staff make to the sector, and we want that to continue.