More than 60 prison guards staged a protest outside Auckland's Mt Eden prison today.

Corrections has threatened that existing prisons will be fast-tracked into private management unless guards agree to prisoners 'double-bunking'.

A Facebook page set up by prison officers to vent their anger could now get them fired instead.

There may be "some merit" in three-strikes legislation for repeat offenders, says Prime Minister John Key.

The man who held a US girl captive for 18 years is now under investigation for a string of unsolved murders.