A paraplegic man on death row in Pakistan is set to hang on Tuesday without the authorities explaining how they will carry out the execution.
The capital punishment is due to take place despite fears over the absence of legal procedures for such a punishment.
Pakistan's prison guidelines require that a prisoner stand on the gallows in order to be hanged.
Abdul Basit, 43, is paralysed from the waist down and uses a wheelchair after becoming ill in prison.
He will become the 240th Pakistani to be executed since Pakistan reintroduced the death penalty in December 2014.
At the time, the government said it was a measure to combat terrorism after the Taliban massacred more than 150 people, most of them children, in a Peshawar school.
The condemned man was convicted six years ago of murder and was to have been hanged in Lahore last month - but this was postponed.
A court has now ordered the jail authorities to go ahead with the hanging, even though his mercy petition filed on 22 July before the president is still pending.
His lawyers argue that hanging him would constitute cruel and degrading treatment.
The prison guidelines do not cover the hanging of a paralysed person, campaigners say.
"[The] jail manual only provides for hanging as a method of execution, and lays down methods to calculate the right length of rope to ensure that hanging does not lead to protracted strangulation," Wassam Waheed, a spokesman for Justice Project Pakistan (JPP) told the BBC.
"The rules presume that the convict [can] walk up to the gallows, which is not possible in Abdul Basit's case."
A trial court issued a death warrant against Abdul Basit on Friday and ordered jail authorities to hang him on 22 September.
Both the Supreme Court and the Lahore High Court have given their consent to the execution.
The JPP has called on President Mamnoon Hussain to stop the execution and "show the world that we protect the lives of those most vulnerable in our society".
Rights groups say that there is a danger that the hanging could go wrong and end up being a breach of the prisoner's dignity - which is protected by Pakistani laws.
In a statement on Sunday the independent Human Rights Commission of Pakistan (HRCP) described the court order to hang Abdul Basit as an offence "against all norms of civilised justice" which would raise awkward questions about the Pakistani justice system and "indict the Pakistani state and society as brutal entities".
The HRCP also urged the president to stay the execution and grant him a reprieve.
Pakistan has the world's largest number of death row inmates, with more than 8,000 people reported to be awaiting execution.
It is on course to have one of the highest rates of executions in the world.