ISLAMABAD - The authorities issued a death warrant on Wednesday for a paranoid schizophrenic convicted of murder, his lawyers said, after the Supreme Court ruled his condition was not a permanent mental disorder and therefore not legally relevant.

Imdad Ali, 50, was certified by government doctors as suffering from paranoid schizophrenia in 2012, following his conviction for the 2001 murder of a Muslim cleric. He is due to be executed on Nov 2, his lawyers said.

They argue he should not be executed because he is unable to understand his crime and doing so would violate the International Covenant on Civil and Political Rights, a UN treaty to which Pakistan is a signatory.

"Imdad's death will serve no retributive purpose, as he remains completely unaware of this reality," said defence lawyer Sarah Belal in an emailed statement.

A government psychiatrist told Reuters he has no doubt about the diagnosis. "I have been treating this man for the last eight years, and there is absolutely no room for doubt in this that he suffers from paranoid schizophrenia," said Tahir Feroze.

On Oct 20, hearing Ali's final appeal, the Supreme Court ruled that schizophrenia is "not a permanent mental disorder" and therefore could not be defined as a mental illness.

With his execution date set, Ali's only hope of a reprieve is a pardon from President Mamnoon Hussain, who rejected an earlier mercy petition in May. Ali's legal team filed a new petition last month.

Pakistan has hanged 425 people since 2014, when it ended a virtual moratorium after a massacre at a Peshawar school where Taliban gunmen killed more than 150 people.

As a last resort, Ali's wife says that she is seeking forgiveness for her husband from the heirs of the murder victim, which could avert his execution under a feature of Islamic law used in Pakistan. "We are trying to contact them, but they are never available to us. We are trying to set a meeting," Safia Bano told Reuters.