The group Human Rights Watch is calling attention to what it calls "severe rights abuses" in a network of secret, unlawful detention centers in China, known as "black jails."
Human Rights Watch interviewed 38 former detainees who described being abducted from the streets, hauled to makeshift jails and detained under harsh conditions. The detainees say they were jailed for filing grievances with the government, seeking redress for losing their land or their houses.
The group released its report to coincide with President Obama's visit to China. In his public remarks and in talks Tuesday with Chinese President Hu Jintao, Obama called for universal human rights.
Brad Adams, Asia director for Human Rights Watch, tells NPR's Melissa Block that the jails can vary from very shabby rooming houses to very small cells. Treatment at the facilities can vary as well.
"Some people report being beaten," he says. "Other people report just being held indefinitely, basically suffering mental torture because they don't know who has taken them and how long they are going to be held."
The former detainees also report deprivation of food and sleep.
The number of people held in these facilities is unknown, but estimates range in the thousands. Adams says it also is unclear what determines how and when the detainees are freed, because there is no due process.
After the report was issued, the Chinese government denied the existence of the jails upon the report's release.
"I can assure you there are no so-called black jails in China," the Foreign Ministry spokesman said. "We put people first, and we are an administration for the people."