Pushing filthy hands between the bars of his cell, Maluel Chol held up a small black plastic bag."This is where I go to the toilet," he said. The 28-year-old has been detained for six months in South Sudan's capital, accused of murder but not yet officially charged and with no access to a lawyer.Hundreds of people detained in South Sudan face such treatment and far worse, a new Amnesty International report says, accusing authorities of torturing people to death and letting many others languish behind bars since civil war began in late 2013.At least 20 people died in detention between 2014 and 2016 and four died last year because of harsh conditions and inadequate medical care, according to the report."It is extremely unconscionable that South Sudanese authorities arrest, torture and ill-treat people in total disregard for their human rights," said Seif Magango, Amnesty's deputy director for east Africa. He called on South Sudan's government to release political detainees or charge them.Hundreds of people have been subject to prolonged and arbitrary detention without charge by the country's National Security Service and Military Intelligence Directorate, said the report, based on interviews with victims and witnesses. Suspected supporters of the armed opposition are increasingly targeted, it said.One man suffered having his testicles pierced with sewing needles while being interrogated about the whereabouts of opposition leader Riek Machar, said the Amnesty report. Other detainees were made to drink water from the toilet and defecate and urinate in front of each other, while some were subjected to forced nudity and genital mutilation.Last year one soldier died in detention while standing trial for a high-profile attack on a hotel in the capital, Juba, in 2016 in which foreigners said they were gang-raped and assaulted and a local journalist was shot dead.South Sudan's government called the new Amnesty report "rubbish" and based on inaccurate information from social media."We don't have a culture of torturing people. We put you in prison to put you behind bars, not to beat you," government spokesperson Ateny Wek Ateny told The Associated Press.As part of a new peace deal, the government in August released more than 20 political prisoners.Despite that act of good faith, South Sudan's political environment has become increasingly intolerant and any criticism of the government can lead to intimidation and detention, the new report says.In July, academic and activist Peter Biar Ajak was arrested at Juba's international airport and accused of treason. He has been detained without charge since then without access to legal counsel or any communication with the outside world, a human rights lawyer involved with his case, Phillips Anyang Ngong, told AP."It's a situation that gives us fear for how the shrines of justice and the institutions concerned will be able to save us from this continued arbitrary arrest of people without charges," Ngong said.According to South Sudan's Criminal Procedure Act, no one should be detained for longer than 24 hours while cases are investigated. The government has signed a UN convention against torture.Even some prison officials acknowledge the system isn't working.At the public prison in Juba more than half of the roughly 1 000 inmates have not been charged or have not had access to a lawyer, director-general Henry Kuany Aguar told the AP.On a recent visit to a detention centre on the outskirts of Juba, AP spoke with several inmates held for days and weeks in squalid conditions without being charged.Two dozen men crammed into three cells lining a narrow, mud-spattered hallway in the county jail, which acts as a transition centre before people are moved to prisons.Hanging his head, inmate Maluel Chol said he had been transferred from cell to cell for months but had not appeared in court or seen a lawyer. Gripping the handle of an empty water jug in his cell, shared with six other men, he said he is discouraged: "I'll just keep being moved around until I die."* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.