"Asghar claimed to be a prophet even inside the court. He confessed it in front of the judge," prosecutor Javed Gul said. "Asghar used to write it even on his visiting card."

Blasphemy is an extremely sensitive issue in Pakistan, where 97 per cent of the population is Muslim, and insulting the Prophet Mohammed can carry the death penalty.

But the country has had a de facto moratorium on civilian hangings since 2008. Only one person has been executed since then, a soldier convicted by court martial.

In 2006, the then-president Pervez Musharraf commuted the death sentence on a British man convicted of murder after appeals from then-prime minister Tony Blair and Prince Charles.

The court also ordered Asghar to pay a fine of one million Pakistani rupees (HK$73,000), Gul said.

A medical board examined Asghar after defence lawyers said he was suffering from some mental disorder, but Gul said they "declared him as a normal person". "Asghar failed to produce even a single witness in his favour," Gul said.

A police official in the Sadiq Abad neighbourhood of Rawalpindi, where Asghar was arrested, confirmed the sentence.

Pakistan's tough blasphemy laws have attracted criticism from rights groups that say they are frequently abused to settle personal scores.

In 2012, Rimsha Masih, a young Christian girl, was arrested for alleged blasphemy in Islamabad. The case provoked international concern because of her age, estimated at 14, and because she was variously described as "uneducated" or suffering from Down's syndrome.

The charges were eventually thrown out and last June she fled to Canada with her family.

Even unproven allegations of blasphemy can provoke a violent public response. There have been several cases where mobs have attacked mentally ill people who have made supposedly blasphemous claims.