Two prison officers were held captive by a group of maximum security prisoners at Tasmania's troubled Risdon prison today. The prisoners injured the guards in a stand-off that lasted for about 30 minutes before other staff responded and they were released, a Corrective Services spokesman said. Details of the injuries were not immediately available, he said. Advertisement: Story continues below Staff hostages were last taken at the prison in November. There have been a series of incidents - including riots, brawls and escapes - at the prison over recent years. Following a report by former Australian Federal Police commissioner Mick Palmer, the Tasmanian government appointed a British corrections specialist as a change manager to overhaul Risdon. Brian Edwards, who held senior positions within the United Kingdom Prison Service, began work in February.