A man who slapped the mother of his children has been told his behaviour was "utterly unacceptable".

Ronald Bruce Tumahuki Simon pleaded guilty to male assaults female when he appeared in the Whanganui District Court on Tuesday.

Police prosecutor Sergeant Stephen Butler said at midday on June 13 Simon struck the victim on the head after threatening her.

Lawyer Harete Hipango said the incident was a "transgression" and Simon's first incident of family violence.


"They are wishing to reconcile," she said. "It was a slap to the head. It was a one off incident."

Judge Philip Crayton sentenced Simon to 12 months supervision.

"You unfortunately lost control, irrespective of what was said to you... that is something that is utterly unacceptable in the circumstances."