They come in search of justice – but end up thrown into jail

They travel thousands of miles to Beijing to bring their problems – land-grabbing, bullying, eviction or abuse by local officials – to the government's attention. But instead of obtaining justice, a shocking new report reveals that many are thrown into sordid and illegal "black jails" where they may be abused, beaten, tortured, raped, robbed, and deprived of food, sleep and medical care.

The Chinese government says such jails are a myth. "Things like this do not exist in China," a Ministry of Foreign Affairs official said in April. In June the government reiterated this stance when an official declared: "There are no black jails in the country." But the publication on the eve of Barack Obama's visit to China of such overwhelming evidence of secret abuse at the heart of the governing system will be a grave embarrassment to his hosts.

Survivors of the black jails have given detailed accounts of the horrors they experienced there. Li Ruirui was 20 years old when she came from Anhui province to petition the government about what she said was mistreatment by her classmates and schoolteachers. But instead of presenting her petition she was locked in a filthy store-room with other petitioners where they were watched over by a gang of thugs, one of whom raped her, she claims.

"The main reason I came to Beijing to petition was that I was mocked in school by my teachers and classmates," she said. "I was forced to go to the Juyuan Hotel ... [where] I was living with more than 10 people in a dining room. Men and women, we all lived together. We slept in bunk beds ... The beds and the room were very dirty and messy. The guards forbade us to go out."

A 46-year-old from Jiangsu province, more than 1,000km from the Chinese capital, cried with fear and frustration as she recalled her abduction. "Two people dragged me by the hair and put me in their car," she said. "My hands were tied and I couldn't move. Then [after arriving back in Jiangsu] they put me inside a room where there were two women who stripped me of my clothes ...[and] beat my head [and] stamped on my body."

A 43-year-old from the same province, who travelled to Beijing to complain about being illegally evicted from her home, which was then demolished, was met off the train by four men who did not identify themselves. "They said I had to co-operate with their work, but they never told me what their work was," she said. She was forced to spend 36 days in a black jail in Jiangsu.

For thousands of years, ordinary Chinese people wishing to obtain justice have travelled to the capital to petition those in authority. The custom survived the transition to Communism and all the upheavals of the past 50 years. For many years, petitioners were heard during the National People's Congress, China's annual parliament. Officially the practice is still lauded by the rulers of the People's Republic. In March, Prime Minister Wen Jiabao praised the system as a "mechanism to resolve social conflicts, and guide the public to express their requests and interests through legal channels".

But in An Alleyway in Hell, Human Rights Watch reveals that, instead of getting a fair hearing for their problems, Chinese citizens are often thrown into improvised cells that may be squalid store-rooms in cheap hotels or rooms in state-owned guest houses, nursing homes or psychiatric hospitals. Government officials, police officers and hired thugs grab them, incarcerate them and intimidate them into giving up their quest for justice.

Sophie Richardson, Asia advocacy director at Human Rights Watch, said: "The existence of black jails in the heart of Beijing makes a mockery of the Chinese government's rhetoric on improving human rights and respecting the rule of law. The government should move swiftly to close these facilities, investigate those running them, and provide assistance to those abused in them."

The reason for locking petitioners up is apparently to slow their flow, discourage others, and prevent them from making trouble for local authorities. The testimony of the victims makes for harrowing reading.

"[The guards] entered without a word, and grabbed me," said one former detainee. "They kneed me in the chest and pounded my lower belly with their fists until I passed out. After it was over I was in pain, but they didn't leave a mark on my body."

The petitioners' complaints range from illegal land grabs and government corruption to police torture. Their first port of call is the "letters and visits" office of their provincial capital. If they fail to get satisfaction from the local officials, petitioners head to Beijing to plead their cases. But in the past few years it has become a dangerous practice. Any petitioners seen near Tiananmen Square, for example, are rounded up and often thrown into the detention centres, which are also known euphemistically as "petitioners' hotels".

The black jails have sprung up since the Chinese government abolished the arbitrary detention of vagrants and other people who arrive in the city without a residence permit. Local government officials are also under pressure to stop petitioners travelling to Beijing and other cities to demand justice, and they have to endure bureaucratic penalties when there is a large flow of petitioners from their areas. As a result they are happy for the petitioners to be locked up and intimidated.

Although the government denies that the jails exist, state media have published reports about them. The majority of the former black jail detainees interviewed by Human Rights Watch were seized without any legal grounds and not told why they were being detained. One of them said: "I asked why they were detaining me, and as a group [the guards] came in and punched and kicked me and said they wanted to kill me. I loudly cried for help and they stopped, but from then on, I didn't dare [risk another beating]."

One former detainee, a 15-year-old girl abducted from the streets of Beijing while petitioning on behalf of her crippled father, was locked up in a nursing home in Gansu province for more than two months and subjected to severe beatings. "To visit these kinds of abuses on citizens who have already been failed by the legal system is the height of hypocrisy," said Richardson.