John Key has admitted he was surprised to find out there are 18 prisoners who have "slipped" their electronic monitoring bracelets currently on the loose.
The Prime Minister said while the number was only a tiny portion of the 3500 prisoners released into the community who are monitored electronically, he was still a "little bit surprised" at the number who have managed to get the bracelets off.
"I don't know all the details about how they're actually getting them off but as a percentage of the people that actually wear an electronic bracelet it's a very tiny fraction of those. Obviously one is one too many.
"The number moves around quite a bit...there are actions that are taken but on balance its still a very small number."
Mr Key told media in Auckland today electronic monitoring was something the Government would be constantly looking at.
But he did not think tightening the electronic monitoring restrictions was a legislative issue.
"There are 18 people at this point that have managed to skip the bracelet, I think it'll be something we're constantly looking at to see if we can make improvements.
"[I was] a little bit surprised, yeah."
The revelation that 18 prisoners were currently without their electronic bracelets came after revelations five criminals serving community-based sentences or on electronic monitoring were on the run after cutting off their ankle bracelets on TV3's Story last night.
Convicted child sex offender David Livingstone was back in court today facing charges relating to allegations he removed his electronic ankle bracelet before going on the run from his Wellington home. He pleaded not guilty.
Last year Tony Robertson murdered and raped North Shore woman Blessie Gotingco while on monitored release for child sex offending.
There are currently 3232 offenders on the electronic monitoring system introduced in February, of which 1832 are also monitored via a real-time GPS system.