Islamabad - Lawyers for an elderly Briton sentenced to death in Pakistan for blasphemy filed an appeal on Friday, saying the court had failed to consider "overwhelming" evidence of his mental illness.
Mohammad Asghar, a British-Pakistani with dual nationality, was sentenced by a court in Rawalpindi, near the capital Islamabad, last week for writing letters claiming to be a prophet of Islam.
British Prime Minister David Cameron has said he is "deeply concerned" about Asghar, who was diagnosed with paranoid schizophrenia in Britain in 2010, and officials have raised the matter with the Pakistani authorities.
A lawyer for the 69-year-old said an appeal had been lodged with the Lahore high court on Friday against both the conviction and death sentence.
"In the appeal the defence has questioned that the court did not follow safeguards available in the law to the defendant who is suffering from mental illness", the lawyer told AFP.
"In addition the overwhelming evidence of his mental illness from UK was not considered by the court despite repeated requests."
The lawyer spoke on condition of anonymity because defending blasphemy cases in Pakistan can bring the risk of reprisal attacks.
Blasphemy is an extremely sensitive issue in a country where 97% of the population is Muslim and insulting the Prophet Mohammed can carry the death penalty.
Pakistan's tough blasphemy laws have attracted criticism from rights groups, who say they are frequently abused to settle personal scores.
Asghar's family say the allegations against him stem from a property dispute with one of his tenants.