When she refused to sign a form renouncing her faith, Wang Chunying said she was handcuffed between two bunkbeds for 16 hours, deprived of food, water and sleep as she felt her wrists bleeding.
"The police would kick the beds apart to the point that my body couldn't stretch any further," she recalled of the time in a Chinese labor prison in late 2007.
"The pain that I had to endure was beyond words. The handcuffs already touched the bone and police still kept tightening them to make them hurt more."
Wang, who now lives in the United States, belongs to the Falungong, a spiritual movement banned in China in 1999. Practitioners have long spoken of abuse at "re-education-through-labor" camps as authorities try to stamp out the faith.
The accounts received new attention from an unlikely source in April, when Chinese cultural magazine Lens broke through the strict censorship and published an article on the Masanjia women's camp, where Wang spent more than five years.
The magazine described detainees being hit with electric prods on the face, hung by the arms, shackled to seats bent forward and forced to sit on "tiger stools" in which prisoners were cuffed into painful positions for hours.
The article was quickly scrubbed from the Internet, but it raised speculation that Chinese opponents of such harsh detention methods may have been sending a message.
"It's remarkable that they published that in China," said Corinna-Barbara Francis, who has researched Masanjia and other labor camps in China for Amnesty International.
"I agree that it's unlikely that an article exposing that level of human rights abuses would have been published if the magazine had not had some behind-the-scenes support."
Voices within China's legal establishment and universities have called for changes. China's new premier, Li Keqiang, said in March that the government may present a plan by the end of the year to reform the re-education camp system.
But Francis said that purported statements by officials on closing camps have quickly vanished, meaning that little is known on the extent of reform efforts.
However daring, Lens magazine did not directly mention the Falungong.
Masanjia, which lies in northeastern Liaoning province, is believed to have been set up to target the Falungong but also imprisons common criminals and citizens who annoyed authorities through petitions on their grievances.
The Falungong are said to be recalcitrant in refusing to sign forms to renounce their faith, which combines elements of Buddhist, Taoist and Confucian philosophies and is known for its breathing exercises.
China declared the movement an "evil cult" after it demonstrated its organizational clout.
Wang said that she and the hundreds of other practitioners at Masanjia sat each morning from 8:00 to 11:30 listening to anti-Falungong videos and guest speakers. She would then be forced until 9:00 pm to manufacture artificial flowers.
"A lot of people would cough and get rashes from the chemicals. I couldn't even breathe whenever I smelled them," she said.
Zhang Lianying, who was also sent to Masanjia, said she and her husband were subjected to particularly harsh treatment after they discussed the Falungong's plight with a European Union official ahead of the 2008 Beijing Olympics.
She said that more than a dozen policemen and inmates pinned down her husband, stripping him of clothing and abusing him across his body with electric batons and clubs.
While Masanjia is considered the premier labor camp, former inmates recounted similar abuse at other locations.
A 2009 United Nations report estimated that 190,000 Chinese were locked up in re-education camps, which were first set up in the 1950s, although officials have said the total is 60,000.
Ma Chunmei said she was arrested in Tiananmen Square after heading to Beijing as part of the Falungong.
At a camp in northeastern Jilin province, she said she was forced to work for up to 19 hours a day producing chopsticks, toothpicks and children's books.
In one session, Ma said that policemen beat her simultaneously with two electric batons and stomped on her.
"I felt my heart was going to jump out. I was vomiting blood, but still I refused to sign," she said.
She has since moved to the United States but said that her sister, Ma Chunling, was sent last year to Masanjia.
Former prisoners said that guards appeared to be motivated by making quotas on sworn statements and threatened inmates not to reveal the harsh methods. Ma said that her interrogation room's windows were covered by newspapers.
"They are afraid for people to know about this because it violates the law and their own consciences," she said.
Former China labor camp detainee, Wang Chunying (L), demonstrates a position she was forced to take while handcuffed between two beds as her compatriot Ma Chunmei looks on during an interview at the AFP offices in Washington, DC, on April 30, 2013.
Falun Gong practitioner, Ma Chunmei, holds a photo showing a prisoner handcuffed between two beds and the marks left by handcuffs, as she and Wang Chunying are interviewed at the AFP offices in Washington, DC, on April 30, 2013.
Ma Chunmei (R) and Wang Chunying are interviewed at the AFP offices in Washington, DC, on April 30, 2013. The women described their detention and torture at a Chinese labor camp for refusing to denounce Falun Gong.