IMMIGRATION powers should be devolved to the Scottish Government to stop families being broken up through "unfair and unworkable" visa restrictions, according to an SNP MP.

The call comes from Anne McLaughlin MP, the party's shadow spokesperson on civil liberties, as the party's Westminster Justice and Home Affairs team prepare to launch new research on the suffering that income restrictions on family visas are inflicting on UK citizens across the country.

The study, to be released on Thursday, comes less less than two weeks after the deportation of Singapore national Irene Clennell, who has been separated from her British husband, children and grandchild.

The research found that children were sometimes denied seeing a parent for months or years because they were unable to secure leave to remain. Others were forced to meet in a third country because even visitor visas were denied.

In a survey for the report 29 SNP constituencies across the country said they dealt regularly with the issue, 16 of them on a weekly basis and three on a daily basis. Statistics show about half of Scots would be unable to sponsor a foreign spouse under current rules.

The restrictions – which means British citizens sponsoring a spouse must earn £18,600 with additional amounts required for dependent children – were upheld by the Supreme Court last month, though it also ruled that the Home Office had failed in its duty to promote the best interests of an estimated 15,000 children involved in such cases.

The SNP believes the restrictions disproportionately affect Scots as wages are lower here than in England.

McLaughlin said the "unacceptable" rules were causing distress and suffering and also damaging the Scottish economy. “The evidence shows that these one-size-fits-all rules make no sense and aren’t working for Scotland," she said. "People who could be united with their loved ones, who would make a valued contribution to society, and a valuable contribution to the economy, are instead being excluded.

"Instead of obsessing over damaging and arbitrary targets and adding to the hostile environment that is turning skilled migrants away, the UK government should reform the rules, and devolve immigration powers, so we can create a system that meets Scotland’s needs.”

Independent researcher Helen Baillot, who carried out the study, said: “What this research showed was how often immigration rules were impacted on British citizens. We also found that it was having a huge effect on children who haven’t seen one of their parents or months or even years."

She claimed that one of the main frustrations expressed was that most said their partners would be able to make a good living if given the opportunity. "Their partners were often highly skilled and yet their potential contribution was not taken into account" she added. "Likewise third party support – from parents for example – does not count."

A spokesman for the Home Office said: "The current rules remain in force but we are carefully considering what the court has said in relation to exceptional cases where the income threshold has not been met, particularly where the case involves a child.”