A convicted armed robber yesterday won a landmark legal case claiming that a recorded message on his telephone calls breached his human rights.

Stewart Potter lodged a case against the Scottish Prison Service, complaining that the message on prisoners' outgoing telephone calls breached his right to privacy.

Potter, who is in Glenochil Prison in Clackmannanshire, said the recorded message which states "this call originates from a Scottish prison" was embarrassing and "inhibited his social rehabilita- tion".

The news comes as three other prisoners launched a bid to halt the Scottish elections in May.

Dates were set in court yesterday to hear the cases of three inmates who claim that the ban preventing them from voting contravenes their human rights.

Derek Traynor, who is serving a life sentence, and James Fisher, who is serving a nine-year sentence, are seeking a court order to ban the Scottish ministers from "carrying out any act to facilitate or promote the holding of the General Election for membership of the Scottish Parliament".

Donald Birrell, who was recalled to custody after being released on licence, wants a judge to order that he be freed so he can register to vote.

Earlier this year, three Court of Session judges ruled that a blanket ban on inmates voting was not "compliant" with the European Convention on Human Rights. The judgment contained scathing criticism of ministers for failing to ensure prisoners would be able to vote in May as they already knew it would breach European law.

There are now 300 prisoners making similar claims.

After a hearing at the Court of Session in Edinburgh yesterday, Lord Clarke set a two-day hearing in the Traynor and Fisher cases for the last week in April. Birrell's action will be heard later this week.

Both cases have provoked criticism from politicians but Tony Kelly, the solicitor for the different prisoners involved, last night said ministers and the prison service were warned in plenty of time and could have averted the court action.

In the Potter case, the judge ruled yesterday the telephone message was unlawful under the human rights convention.

Lord Glennie cited Article 8 of the convention, which provides that everyone has the right to respect for his private and family life, his home and his correspondence.

He said: "In some societies it might be regarded as obvious that a person convicted of a criminal offence and sentenced to a period of imprisonment should, for the duration of his imprisonment, be deprived of his civil rights. Such a notion has no place in our society."

Potter is serving a 21-year sentence imposed after separate convictions for assault and robbery.

His lawyers argued that the message alerted his children's school to his incarceration. It was claimed that the information was not relevant to his dealings with teachers and others.

The prison service said the recorded voice was justified, and cuts nuisance calls by allowing people to hang up if they do not want to take them. It is expected to appeal against Lord Glennie's decision.

Commenting on the Potter case, Annabel Goldie MSP, Scottish Conservative Leader, said: "I am fed-up with the rights of the law-abiding majority being trampled over by the ridiculous grievances of convicts.

"Is this symptomatic of the Scotland we live in now, where one convict's dislike of a perfectly acceptable telephone warning system changes that system?"

Kenny MacAskill, the SNP justice spokesman, said: "This is outrageous. People who breach the law must pay the price. Hard-working taxpayers' money is being used to fund these legal aid cases."