Australian prison officers used a "chemical agent" to break up a siege by 26 inmates at a prison on Australia's southern island state of Tasmania, officials said Monday.

In a statement, Tasmanian Director of Corrective Services Peter Hoult said 26 prisoners who seized control of a wing at Risdon Prison in the state capital, Hobart, on Sunday surrendered soon after members of Tasmania Prison Service Tactical Response Group used the chemical.

The statement did not say what kind of chemical was used but said inmates exposed to it were decontaminated after they surrendered. Nobody was reported injured in the siege.

The prison is home to Australia's worst spree killer Martin Bryant, who shot and killed 35 people at the historic Port Arthur convict settlement 10 years ago.

The inmates took control of part of the prison Sunday morning when they overpowered an officer.

Greg Barns, spokesman for a group called Prison Action Reform said prisoners were protesting lack of access to a sports ground in the prison.

"The understanding of PAR is that access to the sports oval at the prison has been severely restricted since the riot, or the siege, last May, and that needs to be addressed," he told Australian Broadcasting Corp. radio.

"Prisoners live in Dickensian conditions in the current Risdon Prison -- their access to exercise is fundamentally important and they haven't been able to get that access."