Human Rights Watch says patients in Vietnamese drug rehabilitation centers are subjected to years of abuse and forced labor without receiving proper treatment to overcome their addiction.

In a report Wednesday , the New York-based watchdog says Vietnam imprisoned more than 300,000 people without due process in the centers between 2000 and 2010.

The rights group says former detainees described being forced to work for six days a week processing cashews, sewing garments or manufacturing other items, often for little or no pay. They say they were beaten and shocked with electric batons, and subjected to long periods of solitary confinement.

The report says its findings are based in part on interviews with 34 former detainees who were held at 14 centers in and around Ho Chi Minh City.

It says few drug users succeed in breaking their habit at the centers. It cites reports showing between 80 and 97 percent of patients relapse after receiving treatment.

Because of the link between intravenous drug use and AIDS, many of the patients at the centers are HIV-positive. Human Rights Watch says financing for drug treatment programs from international donors, including the United States, has the unintentional effect of helping Vietnam to keep these people detained.

Under Vietnamese law, HIV-positive detainees have a right to be freed if the center cannot provide appropriate medical care.