The deportation and removal of British citizens from Sweden over Brexit residency rights is damaging relations with the UK amid efforts to reset positive associations with London, a Swedish MP has said.

Häkan Svenneling, representative for Vârmland, where a 78-year-old British widow, Joyce Thomas, has been given four weeks to leave Sweden after 21 years of residency, has written to the migration minister, Johan Forssell, asking what he “intends to do to stop the deportations”.

Sevenneling, who is an opposition MP for the left, is to meet Thomas on Wednesday, exactly a week after she was told her appeal had failed over the removal order.

Thomas told the Guardian: “I am in shock. I feel sick. An individual’s life is at stake at my age. It is hell. I have done nothing wrong.”

The retired nurse moved to Sweden with her financier husband, to be closer to one of their sons and their grandchildren, when she was 57.

Her husband, who died of cancer in 2023, did all the administrative work in the household, but both Thomas and her friends have said repeatedly they checked if they had to complete any forms to remain in the country after Brexit, and were told they did not.

Thomas made a late application to remain in Sweden in 2023, just weeks after they returned from the UK, but missing the deadline of 31 December 2021. She and her friends testify that her husband checked whether Brexit was going to affect their residency and they were told they did not need to do anything.

Thomas, who is self sufficient and is not drawing benefit from the Swedish state, has spoken to the “hell” she is now in with the threat of imminent removal, separating her from her family, strong network of friends, and her husband’s grave.

Svenneling says in his letter to Forrsell that Britons lawfully in Sweden before the UK’s exit from the EU would see their “existing residency rights continue to apply” under the withdrawal agreement (W/A).

“It was not intended to result in elderly people who had lived in Sweden for decades losing their rights to remain because of a missed deadline or deficiencies in their application [to stay],” he said.

Svenneling’s written parliamentary question adds to growing pressure on the prime minister, Ulf Kristersson’s, centre-right minority coalition to address increasing concerns over the way Sweden is implementing the EU-UK withdrawal agreement, an international, legally binding, treaty.

“The United Kingdom has long been an important partner for Sweden in a wide range of areas. It is clear that the deportations now taking place are damaging bilateral relations between Sweden and the United Kingdom,” Svenneling said.

He raised the case of Thomas, but also of another elderly Briton, Horace George Mason, 74, who has dementia and Parkinson’s and is in full-time care. Thomas moved to Sweden 25 years ago to be closer to his son Carl and his grandchildren. He, too, was given four weeks to leave.

His family tried a second legal route for him to remain in Sweden, arguing he had rights, under the European conventionon human rights, to stay close to family on whom he relied. But the migration court of appeal ruled that “the state’s interest in regulated immigration outweighs Horace Mason’s interest in continuing to reside” in Sweden.

Writing in the Guardian, David Milstead, who heads the campaign group Brits in Sweden, said the group raised the alarm over Sweden’s approach as far back as 2020 and the safeguards put in place were “untested”.

“Among genuine missed-deadline cases brought to our 9,000-member group, we cannot verify one in which Sweden accepted the reasons for applying late,” he said.

The UK Foreign Office said it has repeatedly raised concerns with the European Commission “that Sweden is taking a considerably stricter approach” to late applications than any other EU member state, with a disproportionate number of refusals.

It is so concerned that it said it appeared that “in practice, individuals are not likely to have their reasonable grounds [for a late application] accepted”.

Milstead is concerned that Sweden’s wider migration policy could be affecting decisions made under the EU-UK withdrawal agreement, and has called on the European Commission and Sweden to urgently address the issues.

“Sweden’s migration politics have moved sharply towards restriction. That cannot displace EU law, but it makes remedial action harder to defend politically,” he said.

The migration agency in Sweden said it was unable to discuss individual cases, but that not knowing a Brexit application had to be made to remain in the country was not a “reasonable ground” to stay.