The Privacy Commissioner, Karen Curtis, said her office will be discussing the issue with ACT Corrective Services in coming weeks.

In the United States RFID tags are already in use.

The Minnesota Department of Corrections is rolling out a $US500,000 RFID inmate tracking system in July to boost security and automate the monitoring of prisoners.

It will track 1300 sex offenders with a department spokesperson claiming it is a "powerful management tool" that can change the way prisons are managed.

"It allows correctional staff to engage in other tasks, such as drug sweeps, instead of just monitoring inmates," the spokesperson added.

The tracking system is based on active RFID tag technology and provides alerts if something abnormal is going on, such as a fight among the inmates.

Under the system, both inmates and corrections guards carry a proprietary RFID tag -- inmates get wrist straps, guards get pager like devices -- that sends out a signal every two seconds to antennas installed inside of the facility and around its perimeter.

The readers feed information into the proprietary management application that sends the data to a master terminal in a control room as well as to client terminals placed in strategic locations throughout the facility, such as the warden's office.

It's up to the prison administrators to decide what the exceptions are. They could include any time a prisoner gets within 10 feet of a fence or when two rival prison gang leaders get too close. If there is an exception, such as a fight or if an RFID strap is torn off, the rules-based software detects it immediately.

The monitoring screen goes from green to red and sends out an audio alert. Once an alert is issued, the screen shows where the trouble is and identifies nearby guards and prisoners.

If it's a gang fight or a hostage situation, the staff will know the identities of everyone involved and what the threat level is based on and the histories of the offending inmates, which are kept in a database.

It can also be used to document prison processes, such as whether a diabetic inmate has received his medication or not.

- with Sandra Rossi and Marc L. Songini