Mirza Tahir Hussain was due to be hanged on Sunday Hussain's plea

Mirza Tahir Hussain, from Leeds, was jailed in 1988 for killing a taxi driver. His execution, scheduled for last week, was not carried out.

In the handwritten letter, published in the Times newspaper, he asked Mr Blair to press Pakistan's President Pervez Musharraf for his immediate release.

Downing Street said Mr Blair had raised the case with the President.

"The issue has also been raised by Foreign Office officials with their Pakistani counterparts," a spokesperson added.

Hussain pleaded with the prime minister to raise his case "most emphatically" with the Pakistani leader and press for his release.

I request all to keep up their support and prayers Tahir Mirza Hussain In full: Death row letter

"I hope President Musharaf [sic] will be obliged to do this and set me free," he wrote.

Hussain was convicted of murdering the taxi driver in the district of Chakwal in 1988 when he was 18 years old.

He had argued that the taxi driver tried to sexually assault him at gunpoint. In a scuffle, the gun went off and the driver was killed.

The Lahore High Court acquitted him in 1996, but a week later it was declared that some of the offences came under Islamic law.

The Federal Shariat Court reversed the decision of the High Court and meted out the death penalty to Hussain.

As his execution date approached this year, a number of groups and individuals - led by his brother Amjad - have desperately tried to put pressure on the Pakistani president to intervene.

In September, after the execution was stayed for a month, Amjad appealed directly to Mr Blair to step in.

The Prime Minister reportedly took up the issue during a private meeting with President Musharraf in London last week.