Rights advocates in Vietnam are criticizing a form of treatment used by the government to rehabilitate illegal drug users and sex workers.
In a newly released report, the international human rights group Human Rights Watch says the so-called therapy is little more than forced labor.
Surrounded by fences or walls and watched over by guards, Vietnam's drug rehabilitation centers provide what the government calls labor therapy to treat thousands of addicts every year.
But this week's report by Human Rights Watch contests how much good the camps actually do, with accusations of forced labor and torture from former detainees.
There are more than 100 drug rehabilitation centers in Vietnam. Under Vietnamese law, drug addicts can be held for up to four years for treatment. Detainees work in a variety of jobs, from agriculture to construction.
The government says the work keeps addicts away from the temptations of the outside world while giving them useful jobs.
However, Human Rights Watch says the centers are "little more than forced labor camps," designed as profit-making machines for businesses.
Nguyen Van Minh, head of the Department of Social Evils Prevention under the Ministry of Labor, Invalids and Social Affairs, says the rehab centers help people recover from their addictions. The work helps addicts recover their health, Minh says, and learn a trade that will help them reintegrate into society when they are released.
The centers first emerged at the end of the Vietnam War in 1975 as camps that provided "re-education through labor." They were given a boost in the mid 1990s as part of a government campaign to eradicate so-called "social evils."
Human Rights Watch says more than 300,000 people passed through the centers between 2000 and 2010. Since 2000, the number of camps has nearly doubled, from 56 to 123.
However, government figures show detained patient relapse rates at 70 to 80 percent. Researchers say that is because the camps are more focused on making money than treatment.
"If you are talking about heroin dependence, you need to have medical assisted treatment and opium substitution such as methadone," said Eamonn Murphy, UNAIDS country coordinator in Vietnam.
Murphy adds therapy camps actually harm detainees because they delay treatment. He says camp conditions encourage the spread of drug-resistant tuberculosis.
"The issue here is you cannot wait until someone is very sick before you introduce them to treatment because the benefits of the treatment are limited," says Murphy. "So you need to introduce people as early as possible."
Work varies across the camps, from agricultural work to construction. The Human Rights Watch report details one recent resident who worked peeling cashews.
The resin burnt his skin. He said if any detainees refused to work they were slapped. He said if they continued to refuse, they were sent to a punishment room.
Other former detainees interviewed said they had to pay for expenses like food, the costs of which were deducted from their wage. Some said they even owed money upon release.
The report says if the detainees refuse to work they are beaten with electric batons or truncheons.
Vietnamese official Nguyen Van Minh denied the charges. He said drug addicts only work for two to three hours in the rehab centers. In the future, he said, the government will cover their food costs.
There is no public record of companies with commercial or contractual relations with the centers. Human Rights Watch says some products may have made their way into the supply chain of companies who sell goods abroad.
Swiss-based Vestergaard Frandsen was alerted by the rights group after it was discovered centers were producing mosquito nets for the company.
Following an investigation, the company terminated relations with the subcontractors who were involved in commissioning companies to work at the centers.
International donors only have provided limited funding for the centers for more than a decade with programs such as staff training and support for HIV.
Eamonn Murphy, the UNAIDS country coordinator in Vietnam, says compulsory detention is not the answer. Instead, he says, the government should continue expanding voluntary community-based services, which have provided access to effective drug treatment services, including methadone since 2008.
"The community-based program where the government are looking to reach 80,000 heroin-dependent people by 2015 is significant, it's the way to go," Murphy says. "And so far in the last two years there has been a rapid effort by the government to scale up this program. It's now gone from two initial pilot provinces to 26 centers across the country and there are plans for many more."
The United Nations says there is little evidence to prove compulsory detention can cut relapse rates. In fact, the majority of residents in the camps have been detained at least once before.
Human Rights Watch has called on all donors and companies to stop working with the forced detention centers.