Prison authorities are feeling the backlash over using Monmouthshire inmates to fill nearby vacancies. The Ministry of Justice has confirmed that 23 prisoners were working at a Cardiff office, but said they were filling vacant posts. A Prison Service spokesman said: "Prison Service rules are very clear: prisoners employed by outside companies cannot replace existing staff. They can only fill genuinely vacant posts." Furthermore, 40 per cent of the open prisoners' earnings at the call centre go to a victims' fund.