A security guard role created to help prevent staff assaults at Christchurch's Hillmorton Hospital has been labelled as "useless".
There have been up to 30 assaults on nurses per month at Hillmorton hospital's Adult Acute Inpatient Unit and nurses blamed management for not taking their safety seriously.
The Canterbury DHB reluctantly agreed to hire a security guard in May but without the power to restrain patients.
One month on, several nurses said the guard had not made any difference.
One nurse said all the guard could do was stand there and "look scary" and could only intervene after someone was hit, after which they were legally allowed to intervene under common law.
The nurse said that rendered the guard "useless".
Another nurse slammed the move as a "knee jerk" response to stories in the media about staff assaults.
The Canterbury DHB's mental health services general manager, Toni Gutschlag, said the security guard would remain in place as long as they were required while more definitive steps are taken.
"We realise that security guards are limited by the scope of their role...however as a safety measure, and in response to requests for an increased security presence from staff, we believe having a security guard on site is a practical thing we can do as back-up support for our team," she said.
Ms Gutschlag said two action groups have been formed to tackle problems at the unit.
"The groups are expected to make recommendations in 4-6 months although if there are things we can do immediately, or within a week or so, changes to improve safety will be introduced as soon as practical," she said.