Four cases of inappropriate relationships between Corrections Officers and prisoners were confirmed in the past two years.
"It is a sad fact that any large organisation will experience a few who let the side down," Department of Corrections human resources general manager Vincent Arbuckle said.
"The overwhelming majority of our staff fulfil their duties with integrity and commitment, in what is often a pressured and challenging environment."
Two officers resigned, one was given a final warning, and one was dismissed, according to information obtained by The Dominion Post. The incidents happened between July 1, 2010, and June 30, 2012.
The term "inappropriate relationship" refers to any interaction between an employer and a prisoner that breached any operational procedure, or the department's code of conduct. This may include friendships, financial, business or sexual relationships with a prisoner, or former prisoner. Where an activity, behaviour, or conduct was identified as potentially unacceptable, the Department of Corrections investigated and took action if necessary, Mr Arbuckle said.
It had recently introduced a range of initiatives to boost integrity in the workplace.
These included drug testing for all applicants, credit checks for roles with financial risk, and the launch of an 0800 Integrity Line for advice, or to report concerns over wrongdoing.
In July, The Dominion Post reported that Corrections staff feared reprisals over "narking". When asked whether honesty and integrity were valued in the department, only 65 per cent answered favourably.
The survey cost $92,824, and was completed by 78 per cent of staff.
Last year, it was reported at least four female Spring Hill Prison officers left the job in an 18-month period after becoming involved with inmates.
- The Dominion Post