The Islamic Human Rights Commission has pledged to do everything it can to stop the hanging of Mirza Tahir Hussain.
The former Territorial Army soldier from Headingley, who has dual Pakistani/British nationality, has been in prison in Rawalpindi, ne
ar Islamabad, for 18 years.
He was cleared twice in Pakistan's High Court of killing a taxi driver, but is now condemned to death under Sharia law – the strict Islamic code - and is due for execution on June 1, his 36th birthday.
Massoud Sahadjareh, chairman of the commission, has taken up the case after Mr Hussain's family contacted the organisation.
"We have contacted the high commissioner and she will raise the issue in Pakistan," he said.
"We have alerted our 17,000 members here and 7,000 abroad.
"They have been sending emails and letters. In fact, we understand that the Pakistan commission's emails system was blocked because they received so many protest messages.
"We will be organising events over the next two weeks such as public rallies and we will meet with officials."
He added: "It is shocking that it has taken so long.
"No-one was alerted to this.
"All the signs are that he has suffered a miscarriage of justice.
"The whole of his youth has been taken away from him."
Mr Hussain was 18 when he was charged with murdering a taxi driver while he was on holiday in Pakistan.
His family say he was trying to defend himself from being robbed and assaulted.
His initial conviction was overturned in two separate appeals in the Pakistani High Court.
However, Mr Hussain was then condemned to death under Sharia law and that decision was upheld by the country's Supreme Court.
The Foreign Office is in talks with the Pakistani authorities to try to get the sentence commuted.
