Mirza Hussain has been in jail for 18 years

Mirza Tahir Hussain, 36, was due to be hanged on 3 August but was last week granted a stay of execution by the Pakistan President until 1 September.

The delay was granted to give Mr Hussain's family time to negotiate "blood money" with the relatives of the victim - a practice under Islamic law.

But the relatives said they "wanted justice" and "would never compromise".

The family of Jamshed Khan said they had been saddened by the further stay of execution granted by President Pervez Musharraf and described pressure from the British Government as "murder of justice".

Amjad Hussain broke down as he outlined the latest development

Mirza Tahir Hussain, who is of dual British-Pakistani nationality, has been in jail in Pakistan for 18 years for the killing.

He has always claimed he was acting in self-defence, saying the driver tried to sexually assault him.

His conviction was overturned in Pakistan's High Court but he was later retried by an Islamic court, which sentenced him to death.

Mr Hussain's brother Amjad described the family negotiations as "repugnant, medieval and barbaric" and said it was now "high noon" for his brother.

He said: "So far the pleas of everybody have fallen on deaf ears and now I am afraid that Prime Minister Tony Blair has to directly intervene in the matter.