A citizen oversight committee says privately-run prisons in Arizona are not cost-effective and are more difficult to monitor than state prisons.
A report released by the American Friends Service Committee says Arizona paid $10 million more for private prison beds between 2008 and 2010 than it would have for equivalent beds.
The Arizona Republic reports the information was gathered through public information requests and other data.
The American Friends Service Committee says all private prisons should disclose the same information as state prisons.
State law doesn't require private prisons that hold federal detainees and prisoners from other states to inform state or local authorities when there's an escape, a riot or an inmate death.
A spokesman for the state Department of Corrections says they haven't had sufficient time to review the report.