Cambodia's construction boom has pushed thousands of families into modern slavery in the brick industry through debt bondage, a report by researchers from London’s Royal Holloway University say.

The blood bricks report was released on Tuesday following the sharp rise in Cambodian brick prices in the last year due to growing demand from the rapidly developing coastal town of Sihanoukville and Phnom Penh.

Cambodia’s construction industry has boomed with new shopping malls, housing estates, hotels, office blocks, factories and condominiums causing demand for bricks to skyrocket.

This, the report said, has pushed adults and children into a key workforce and trapped them in debt bondage.

“Tens of thousands of debt-bonded families in Cambodia extract, mould and fire clay in hazardous conditions to meet Phnom Penh’s insatiable appetite for bricks. Kiln owners repay farmers’ debts and offer a consolidated loan."

“In return, farmers and their families are compelled to enter into debt bondage with the kiln owner until the loan is repaid,” researchers said.

Chheang Suyheang, the president of two brick kiln associations representing more than 100 factories in Kandal province, denied the existence of child labour in brick factories.

He said there is no negative impact or danger for brick workers due to authorities and local organisations preventing children from working in factories.

“There is no impact on them. Their hands and feet do not fall into the machines or [get] cut off like before because there is no child labour in the brick [industry] and we do not allow minors to work because the organisation has strengthened,” he said.

Suyheang acknowledged that every “brick family” has borrowed money from the kiln owners. This is because they can quickly pay off their bank and microfinance loans since the kiln owners do not charge interest.

In return, he said the families are put to work until the interest-free debt is paid off.

“Everyone is indebted in every brick factory, [whether a lot or a little,] because they borrowed money from the banks after their businesses collapsed."

“Then they borrowed from us to repay the bank as we do not charge any interest. In return, they have to work to repay their debt to us."

“Our loan is like a bond so they cannot leave to work for other brick factories,” he said.

However, one woman, who was identified only as Achariya to protect her identity, said: “My debt keeps on increasing now that I have a husband and children. In the future, my children will do the same – sign their thumbprints to take my place.”

The Ministry of Labour and Vocational Training issued a statement last week warning of using child labour in brick kilns and other forms of exploitation such as debt bondage.

Ministry spokesman Heng Sour could not be reached for comment.