Around 100 EU nationals living in the UK were told by the Home Office that they faced "detention and deportation" – despite the fact that they are legally entitled to live in Britain.
The government department has said the letters, which stated “a decision has now been taken to remove you from the United Kingdom in accordance with section 10 of the Immigration and Asylum Act 1999”, were sent by mistake.
A Finnish academic working at a British university is among those who was told she faced being detained and deported if she did not leave by her own volition.
Dr Eva Johanna Holmberg, a visiting fellow specialising in early British history at Queen Mary University of London, received the Home Office letter after she applied for a "qualified person certificate" for peace of mind, as the future of EU nationals in the UK post-Brexit remains uncertain.
Holmberg is married to a British citizen, pays taxes in the UK and has five years of guaranteed employment with the university. In spite of this, she was told she had one month to leave the country, and faced detention and deportation if she did not comply.
She has now been told to disregard the letter but has already spent almost £4,000 instructing lawyers to fight the decision.
The academic told the Evening Standard: “How can an EU national be deported from the UK? There is free movement of people."
Holmberg said she believed "in the strength of paperwork", and thought a qualified person certificate would only help reinforce her status.
But she added: “It turns out it has spiralled into some Kafkaesque nightmare. It is just unbelievable. All for a piece of paper I don’t even need. It would be funny if it were not so draining and stressful.”
BuzzFeed News has reached out to Holmberg for comment.
As well as contacting lawyers, Holmberg raised the issue with her MP, Caroline Lucas, when she received the letter last Thursday.
Lucas, co-leader of the Green Party and MP for Brighton Pavilion, said: "It beggars belief that my constituent, Eva Johanna Holmberg, who is married to a UK citizen, pays taxes in the UK and has 5 years guaranteed employment as a visiting fellow, was issued with a letter threatening her removal and possible detention.
"The Home Office has now confirmed her status as an EEA qualified person and it seems they acted in error. Mistakes like this are simply not good enough. The government is turning lives upside down by callously playing hard ball over Brexit and it needs to take its responsibilities far more seriously than seems to be happening at present."
Professor Simon Gaskell President and Principal of Queen Mary University of London also criticised the Home Office, saying: “Whilst it is clearly reassuring that the appalling position in which Dr Eva Holmberg was placed has now been resolved, we should be deeply concerned that such mistakes can be made – and, perhaps worse, that we live in times when they do not particularly surprise us.
"Dr Holmberg and her family should not have been subject to such stress, and it should not have been necessary for support mechanisms at Queen Mary University of London to be activated. At QMUL, approximately 30% of academic staff come from overseas; their loss would do irreparable damage to the success (in both teaching and research) and international stature of the university.
" While I have no doubt that these colleagues understand how much their university values them, it is essential that the UK government makes clear that it also understands the huge contribution that they make.”
A Home Office spokesperson said: “A limited number of letters were issued in error and we have been urgently looking into why this happened. We are contacting everyone who received this letter to clarify that they can disregard it.
“We are absolutely clear that the rights of EU nationals living in the UK remain unchanged.”