A FATHER mistakenly assaulted his 13-year-old son after confusing him with his estranged wife's boyfriend, a court heard.

A judge has warned the 43-year-old about taking the law into his own hands after the altercation.

The father, who cannot be named for legal reasons, pleaded guilty at York Crown Court to causing actual bodily harm to his son.

The incident happened when he sneaked into the former marital home in the early hours of a Sunday morning and crept upstairs to confront his wife's boyfriend.

Patricia Mancina, prosecuting, said the defendant received a phone call at midnight from his son to say that he had been injured in a play fight with his mother's boyfriend.

The father, from New Earswick, York, rang the emergency services to report the incident, but they could not attend and, incensed by the circumstances, he went to the house at about 4am.

Climbing through a window and arming himself with a knife-sharpening steel, he headed upstairs to confront the man.

Ms Mancina said: "Unbeknown to him, the boyfriend had left, but his wife and two children were watching television. The defendant struck out twice at a male figure, but it was his son." The teenager suffered damage to his shoulder and a fractured finger.

Simon Perkins, mitigating, said the defendant had been injured in a previous confrontation with the boyfriend and had picked up the knife sharpener for self-defence.

He said the son had behavioural problems and it was the wish of his mother, who had tried to get proceedings against her estranged husband dropped, to retain contact with him.

Judge Paul Hoffman, Honorary Recorder of York, ordered the defendant to serve a two-year community rehabilitation order.

In passing sentence, he said: "You seem a decent family man concerned about the welfare of your children. I can understand man-to-man how you felt, but I do not sympathise with what you did."

Judge Hoffman said he shared the defendant's disappointment that the police did not attend when called. "If they had, you may not have taken the law into your own hands. That is to be condemned and if you will creep into people's houses like a thief in the night, then no good will come of it."

Updated: 10:38 Tuesday, September 02, 2003