London: A man and woman have been arrested on suspicion of encouraging or assisting suicide after allegations that they planned to take a 71-year-old man to the Dignitas clinic in Switzerland so he could kill himself, police have said.

The man, aged 25, and the woman, 65, who are believed to be the son and wife of the man who was to have been taken to Switzerland, were arrested on 8 August, Sussex police said in a brief statement. Both have been released on bail without charge until 8 October while police carry out further inquiries.

Police described the 71-year-old as vulnerable and said officers had arranged for experts to assess his mental capacity to see whether he was capable of taking informed decisions.

The statement added: “It is an offence to encourage or assist suicide under the Coroners and Justice Act 2009 and officers are investigating whether any crime has been committed or is likely to be committed if they do not take action.”

The right of people with terminal illnesses or incurable conditions to take their own lives has been one of the most fraught issues taken through the courts in recent years, with judges considering a series of test cases.

A year ago Tony Nicholson, who had locked-in syndrome after a stroke, died six days after the high court ruled that doctors could not help him to kill himself. The case was taken on by another man, Paul Lamb, and last month the court of appeal rejected his case.

Last year a commission on the issue, chaired by the former lord chancellor Lord Falconer, said parliament should consider changing the law on assisted suicide to allow some terminally ill people to end their lives at home with the help of their doctor.

Police have tended not to pursue charges against relatives who help loved ones travel to the Dignitas clinic, where assisted suicide is legal. However, police have to be satisfied that the person involved was able to make a fully informed decision on ending their life.

— Guardian News & Media Ltd