A group of politicians and academics have called for the release of a British man sentenced to death in Pakistan for blasphemy, so that he can receive mental health treatment.

In an open letter published in the Independent newspaper, the group raised concerns about Mohammed Asghar's wellbeing and asked the President of Pakistan to intervene.

Mr Asghar was arrested in 2010 in Rawalpindi, near Pakistan's capital, Islamabad, for claiming to be the Prophet Mohammed.

His family says he suffers from mental illness and was treated for paranoid schizophrenia in Edinburgh before returning to Pakistan in 2010.

He was convicted last month and his family immediately launched a campaign for him to be released from custody in order to receive medical help.

His lawyers said he appeared "pale, dehydrated, shaking and barely lucid" during a recent visit, prompting fears his condition has seriously deteriorated.

Signatories to the open letter include Labour's shadow Justice Secretary Sadiq Khan, Scottish human rights lawyer Aamer Anwar, academics from the Muslim Institute, the Islamic Society of Britain and a host of charities.

The letter is addressed to Pakistan President Mamnoon Hussain.

It reads: "Like so many British Pakistanis, Mr Asghar was a successful businessman and pillar of the community who lived for many years in the UK where, through a lifetime of hard work, he helped promote the bonds of friendship and understanding between his native and adopted countries.

"We the undersigned are concerned that his recovery from illness is impossible whilst he remains detained at Adiala jail, where his lawyers fear he is in danger of taking his own life.

"We respectfully urge you to consider using your discretionary powers as President to pardon Mr Asghar and to allow him to be released from jail so that he can receive his treatment and be reunited with his loving family."

The blasphemy complaint was brought against Mr Asghar by a tenant with whom he was having a dispute.

His family have appealed to the UK Government to do everything it can to make sure he is safe.

In a statement released through Reprieve earlier this month his relatives said: "As a result of a property dispute with one of his tenants, my father was jailed pending a trial.

"The dates kept being moved forward so that by the time the trial concluded he had already been in horrific jail conditions, sharing a cell with several other men for three years.

"Throughout this time he had minimum access to medication that might have helped his mental illness for three years.

"We are really upset and concerned that they will never release him and that he will die in jail."

A petition on change.org, addressed to Prime Minister David Cameron and Scotland First Minister Alex Salmond, is calling for Mr Asghar's release.

The Foreign and Commonwealth Office (FCO) said it has continuously made representations to the Pakistan government on behalf of Mr Asghar and would continue to do so.

The Scottish Government said it was in touch with the Foreign Office about the case.