Five kiln workers recently bought their release from a labour camp near the capital Islamabad for one kidney each.
All five had been indebted to the camp owner for sums they had borrowed and been unable to repay because of pitiful wages.
"I was forced to sell my kidney to pay off my debt," one of the workers told state-run Pakistan Television.
He was speaking a few days after his rescue, along with 32 other labourers, from a location on the outskirts of Islamabad.
Dozens of brick-kilns in the area employ hundreds of workers including entire families.
Zaman Mir, one of the freed labourers, said camp managers willingly advanced loans to the labourers because it allowed them to employ the indebted on very low wages.
"They do it because the poor labourers cannot pay back loans and end up in perennial bondage," Mir said.
The practice of bonded labour, or using debt as a means to enslave people, has flourished for years in Pakistan despite the existence of the Bonded Labour Abolition Act of 1992.
According to the Human Rights Commission of Pakistan (HRCP), at least 10,000 bonded labourers, including women and children continue to be held in bondage at brick kilns alone, across the Punjab province.
"The issue of bonded labour must be addressed at the national level given the increase in this illegal practice," said Kamila Hayat, a renowned Pakistani human rights campaigner.
"Despite the cold weather, we were kept chained and forced to sleep on the ground under the open sky"
Worker freed from a private jail
Unscrupulous proprietors, mostly backed by tribal chiefs and influential politicians and bureaucrats, even run private jails.
Seven people were recently found locked up at a kiln works near Lahore, capital of the Punjab province, by court officials who managed to secure their release.
"Despite the cold weather, we were kept chained and forced to sleep on the ground under the open sky," said one of the freed workers.
Incidents involving sexual abuse of women workers and children in bondage are also common.
A report by the NGO, Society for Protection and Rights of the Child (SPARC), estimates that there are more than 250,000 children working across the country as bonded labourers, both in the formal and informal sector including brick-kilns, coal-mines, auto workshops and carpet-weavers.
"Most of them were held alongside their families and often laboured in hazardous conditions," the report says.
A senior court in Peshawar, the capital of the North Western Frontier Province (NWFP), recently ordered the release of 25 bonded labourers including 12 children and six women, declaring bonded labour of all kinds unconstitutional.
The judgment was ignored by provincial authorities which refused to follow it up.
"I don’t think the government will ever take stringent action against owners of the brick kilns because most of them enjoy the protection and patronage of influential MPs," said Muhammad Mukhtar, a resident of a village near Islamabad.
The situation in the southern Sindh province is equally grim. Tens of thousands of the 1.7 million “haris” (farm labourers) toil on feudal farms and private homes, with little hope of breaking out of bondage.
The majority of the people work in agriculture, mostly as tenants of big property owners.
Pakistan's slow moving and intricate legal system adds to the woes of these farm labourers.
"I don’t think the government will ever take stringent action against owners of the brick kilns because most of them enjoy the protection and patronage of influential MPs"
"The dismissal of 94 petitions for the release of bonded labourers by the Sindh High Court (SHC) declaring these debt-related disputes between landlords and haris, has encouraged the landlords and added to the difficulties of labourers in bondage," said Asma Jehangir, co-founder of the independent Human Rights Commission of Pakistan (HRCP).
According to SPARC, most of the haris are concentrated in five districts of Sindh – Thatta, Dadu, Badin, Mirpurkhan and Umerkot where debt continues to be used to enslave workers.
Haris are often forced to accept cash advances by landlords, many of them leading politicians. They receive food and clothes, stacking up their financial liabilities.
They (haris) are kept in well-guarded prisons while their women remain vulnerable to sexual assaults and their children exposed to severe beatings and physical labour.
"Women, children and animals are the three powerless segments of our society, whose voices remain unheard," said Firyal Gohar, a well-known social activist who has made several documentaries on women’s issues.
HRCP has disclosed in one of its recent reports that trafficking of bonded labourers continues to be a common practice among landlords.
Haris are sold by one landlord to another, usually for a price higher than the accumulated debt they had obtained from their previous master, thereby further increasing his debt.
Most of the 41.5 million people in Pakistan’s labour force continue to face acute difficulties as a result of soaring unemployment.
"It’s unemployment which has given birth to social injustices including bonded labour," said Senator Farhat Allah Babar, of Benazir Bhutto’s opposition Pakistan Peoples’ Party.
Others believe that strict implementation of bonded labour laws is the only way to eliminate the practice.
Economic experts say that unless the government can create more jobs in the industrial sector, there is little hope for millions of Pakistanis who remain trapped in debt and poverty and exposed to abuse.