It cost £1,135 a week or £59,020 annually to keep an offender in prison last year, according to statistics released by the Minister for Justice, Mr O'Donoghue. In a written reply to Mr Ivor Callely, (FF, Dublin north-Central) the Minister said the cost was calculated by averaging out the running costs against the average number of offenders and those running costs "include certain items which are fixed no matter what the number of prisoners in custody, such as officers' wages and lighting and heating".