Ms Crowe and her band members fell foul of a little known UK immigration law which states that performers from outwith the EU must have a certificate of sponsorship from the venue at which they plan to perform to gain entry to the UK.

She was due to tour the UK and spend time with friends in north-west Sutherland, but then suffered an 11-hour ordeal in which she was locked up and had her fingerprints taken before being barred from the UK and deported.

Nationalist MSP Mr Gibson had watched Allison Crowe sing during the Northern Lights John Lennon Festival in Durness two years ago. He heard about her plight from Lily Byron of Rosehall, who read about it in the NT.

"This is a crazy policy and a disgraceful way to treat a legitimate visitor," he said this week. "I very much enjoyed her performance two years ago in Durness and am absolutely scunnered by the fact that she and her band will not be able to visit there or perform in the UK due to a draconian and ludicrous dictate from the Home Office.

"She and her band members were treated as common terrorists, which is sickening. The Home Office could learn from the German authorities, who said they were horrified by the way in which Allison was treated by the British and have warmly welcomed her for her tour. Also it seems that Austria and the Czech Republic have no problems with Ms Crowe and her band touring there.

"This law has to repealed as soon as possible so that the culture of Scotland and the wider UK is not tarnished."

The SNP member added that he had contacted Allison's agent and manager, Adrian Du Plessis, about the matter and had submitted a written question to Culture Minister Mike Russell.

"My friend Lily Byron asked for my help and I took action straight away," Mr Gibson said. "Allison deserves our support and I have engaged my Westminster colleague Pete Wishart MP – the former Runrig member – to take the case forward."