A prison officer who was assaulted by an inmate has been stood down, the inmate's lawyer says.

Defence lawyer Debbie Goodlet said there was an investigation going on at Whanganui Prison in relation to a previous incident between the officer and the inmate.

Her client, Joshua Ian Morton, was in an exercise yard on May 28 with another inmate, police prosecutor Sergeant Rachel Willemsen said in the Whanganui District Court on Tuesday.

The victim unlocked the gate to the yard to put another inmate inside, and as the gate opened Morton swung punches at him.


A scuffle ensued between the pair, until other Corrections officers were able to intervene.

Morton explained he'd had a disagreement with the victim earlier in the day, and thought the victim was coming to continue the argument.

He pleaded guilty to assault on a prison officer.

Ms Goodlet said Morton and the victim had had issues in the past.

Judge David Cameron said prison officers' jobs were "difficult enough without having inmates launching attacks on them, irrespective of the underlying reasons for that".

He sentenced Morton to one month in prison.