A riot that broke out at a Hunter jail on Thursday - with inmates locking themselves in rooms and some reportedly seen lighting fires on the roof - was over a call for drug withdrawal therapy, the state's prison authority says. Prison sources say anger over COVID-19 restrictions, which had robbed inmates of personal contact visits, sparked the incident. Corrective Services NSW says the H-block prisoners wanted opioid substitution therapy made available to help with withdrawal cravings brought on after the supply of illicit drugs stopped when social visits were suspended. Australian Community Media understands more than a dozen maximum security prisoners at Cessnock's Shortland Correctional Centre took the action just before lunchtime on Thursday. A Hunter woman with two family members serving time at Cessnock told the Australian Community Media she was worried because the riot had broken out in the wing where her son was being held. READ ALSO: She said she had spoken with another family member, who is a prisoner in one of the other Cessnock jails, about 12.30pm. "He said it was really bad - he said they were starting fires on the roof and then the phone cut out," said the woman, who asked not to be named. "He was worried - he's not easily rattled." Prison sources said the riot was because prisoners were angry and upset about the COVID-19 restrictions that had robbed them of their personal contact visits. The outburst began at about 11.30am. They said that at one stage at least 17 people had been on the roof of the Shortland Correctional Centre, one of three jails at the expanded Cessnock jail complex. Shortland holds about 450 prisoners, including murderers and other serious criminals. "One bloke was up there in shorts and a singlet, he'll be getting cold," the prison source said, referring to Thursday's wet and windy weather. Sources said the Department of Corrective Services had stopped prisoners' visits some weeks before, replacing them with video contact. "They were allowed an hour a week under the usual scheme, and the video calls are 20 minutes, so they don't lose that much, but you're right, that's how a lot of the contraband gets in, so people have been getting itchy about not having their drugs or steroids or whatever," Australian Community Media was told. This included tobacco although the jails were supposedly smoke-free. Sources said similar protests had taken place in recent weeks at Goulburn, Wellington, Kempsey, Long Bay and Parklea jails. "Looks like it's our turn now." Sources said there was no doubt the coronavirus restrictions were the reason behind Thursday's riot. "It makes it much harder to get contraband into the jail. There's still stuff thrown over fences but we get most of that." One prison source said people needed to realise the difficulties that prison officers faced in dealing with such situations. They believed the prisoners would be left up on the roof until they "worked off their anger" before being coaxed down or allowed to come down of their own accord. "Someone inside for murder doesn't have much to lose in situations like these," the source said. Corrective Services NSW said prison officers secured the inmates by 4pm, including some who had made their way to the roof of an internal building at midday. The prison authority said no staff or inmates were injured and it was investigating the incident. "Correctional officers work in a challenging environment and are well equipped to deal with the difficult situations they sometimes face as part of their day-to-day duties," Corrective Services NSW deputy commissioner Luke Grant said. "Our officers are highly trained to respond to these incidents and I commend the Shortland officers and the Security Operations Group for their skilful handling of this situation." As of Thursday evening, there had been no confirmed cases of COVID-19 in NSW prisons. Corrective Services NSW has introduced a range of measures in an effort to stop coronavirus infection and spread inside the state's prisons. The authority announced in March it had suspended all social contact visits at NSW jails because of the pandemic. "Like the rest of the community, it's important we minimise all potential cases of COVID-19 in our prisons," commissioner Peter Severin said at the time. "Our focus remains on protecting staff and managing risks to ensure that we maintain safe and secure operations within all our work locations." But Dr Mindy Sotiri, program director with advocacy group Community Restorative Centre (CRC), told the Australian Community Media on Thursday night people inside NSW jails and their loved ones were "doing it tough" under the measures. "While the restrictions on family visits in NSW prisons right now are a necessary response to the high risk of COVID-19 transmission within NSW correctional centres, there is no doubt that this is causing considerable distress for incarcerated populations and for families on the outside," she said. "When the men and women CRC works with are locked up, connection with loved ones through visits is a huge part of what can make prison tolerable. "It is a way to maintain links with family and children and community, which is critical to reduce re-offending on release, and also a really big part of maintaining an identity outside of the prison walls."