Six years after China took steps to crack down on torture by police, detainees continue to be beaten, hanged by their wrists and shackled to iron chairs, New York-based rights group Human Rights Watch said on Wednesday (13 May).

The report comes six months before China is due to face scrutiny by a UN panel against torture, and following a pledge by President Xi Jinping to boost the rule of law.

The ruling Communist Party is looking to quell public discontent over several high-profile miscarriages of justice, with China's top court unveiling legal reforms in February to halt the use of torture to gain evidence

Police have got round government measures introduced since 2009 to curb abuses by interrogating detainees outside official detention centres or adopting methods that leave no visible injuries, the group said.

The abuse of suspects remains a serious problem, said China Director of Human Rights Watch, Sophie Richardson.

"The report that we released today looks at how effective new measures adopted between 2009 and 2013 are at curbing wrongful convictions. But what we found is that not only does this ill treatment in detention for criminal suspects remain a serious problem, very few of those mechanisms are really working the way they're supposed to," Richardson said.

The report cited former detainees as saying they were physically and psychologically tortured during police interrogations, including being beaten with electric batons, sprayed with chilli oil and deprived of sleep.

Richardson said common torture methods include beatings and strapping suspects onto metal interrogation chairs known as tiger chairs.

"Some of the most common ones are about physical beatings, either by police or by guards, particularly by cell bosses, who are other detainees who have been identified to help 'maintain order' in cells. We documented a number of cases involving shackles, people confined in what are called tiger chairs, for days, weeks, months, one case, years at a time," she said.

The report was based on interviews last year with 48 recent detainees, members of their families, lawyers, former officials and an analysis of court verdicts in China.

Police may subject detainees to 37 days of interrogation incommunicado before prosecutors have to approve their arrests, it added. Lawyers are not allowed access during interrogations. It also said China's criminal justice system gives the police excessive powers over the judiciary, hindering any efforts at accountability.

Measures such as giving the judiciary instead of the police control over detention centres would improve the situation, Richardson said.

"I think there are two or three steps the government can take very swiftly that will change the situation. The first would be to allow detainees to have access to lawyers during interrogations, to ensure the right to silence. Certainly, transferring control of detention centres from the Ministry of Public Security to the Ministry of Justice could help. Providing support services and compensation to survivors of torture. There are very few available now and we think that's critically important," she said.

The report focused only on suspects of non-political crimes, such as robbery and organised crime, but torture of political criminal suspects is often worse, Human Rights Watch China Researcher Maya Wang said.

China's Foreign Ministry, and the Ministry of Public Security, which runs the police force, did not respond to requests for comment.