A police officer who specialised in tackling hate crime repeatedly punched a 14-year-old boy after the teenager taunted him, a court has heard.

PC Paul Evans, a hate crime officer with South Wales police, allegedly attacked the boy after his mother called the police to her home in Bridgend.

The boy sustained bruising to his face, a chipped tooth and a bleeding nose, Cardiff magistrates court was told.

The court heard Evans and a colleague went to the house after the boy’s mother reported that he had been punching the walls and had grabbed a knife, threatening self-harm.

When Evans and his colleague arrived, the boy was locked in the bathroom talking to a friend on the phone, it is claimed.

Evans forced his way in and is alleged to have thrust his forearm into the boy’s throat.

Vaughan Pritchard-Jones, prosecuting, said: “The boy became abusive … calling them pigs. This further annoyed and frustrated Evans.”

The officer is alleged to have grabbed the boy’s phone, but when he could not turn it off, the boy called him a “pussy”.

Pritchard-Jones said: “For Evans, having been frustrated and annoyed, being called a pussy was the final straw, and he reacted by punching the boy in the face.”

The boy alleges that Evans told him he was “doing his mother a favour” before punching him two more times in the face.

In his video interview, the boy described the attack as “scary”, saying: “It all happened so quickly. Evans was calling me a disgrace. He told me that if I was his son, he’d do the exact same to me. He was saying horrible, horrible things to me.”

The alleged attack was stopped by Evans’ colleague, PC Lauren Evans, who pulled him away.

Evans arrested the boy for affray despite no reports or complaints of that nature, and allegedly did not caution him, the court heard.

The court was told the boy had once made a hoax call to police claiming to have found nail bombs at his school.

The boy’s mother told the court how she heard a female police officer say: “Stop it, what are you doing?”

His mother said: “After he came down he was terrified and I could tell his nose had swollen. I was just shocked, I didn’t know what to do. I was scared. Terrified. I couldn’t believe what I’d seen.”

She told magistrates how she called police many times because of her son’s “erratic behaviour”.

She said: “He’s very unpredictable. He can just go off his head for no reason. He punches things, damages thing and throws things. I’ve called the police about 20 times to get support when he has an outburst.

“I told the police officers to have a word with him, to try and frighten him. I know he’s scared of being arrested so I just asked them to have a word.”

Evans, 50, of Bridgend, pleads not guilty to assault.

The trial continues.