A female guard at Rimutaka Prison has been suspended for allegedly assaulting a younger male inmate.

Upper Hutt woman Anastacia Te Paia Wihare is accused of striking the man with a clipboard and punching him in the face with an upper cut on August 17, the Dominion Post reported.

The newspaper said it was also understood Ms Wihare had faced investigation last year for allegedly having inappropriate relations with an inmate during a sleepover at the prison's Maori Focus Unit.

The Corrections Department yesterday confirmed a guard had been stood down, but refused to release closed-circuit television footage of the assault or reveal whether the prisoner had been injured or received compensation.

It said it demanded a high standard from its staff and had a duty to investigate allegations of misconduct.

Police confirmed they had been contacted by the prison, but had referred the matter back for internal investigation.

Ms Wihare declined comment.