A 15-year-old boy killed a man amid claims he had tried to kiss his girlfriend.

The teenager attacked Jack Wilson in Holytown, North Lanarkshire, last October.

The youth, who cannot be named for legal reasons, punched the 20-year-old moments after telling another youngster "watch this".

Jack never recovered after suffering a fatal head injury.

The schoolboy now faces being locked up after pleading guilty to culpable homicide at the High Court in Glasgow.

A judge continued his bail pending sentencing next month.

Jack had been out with different friends before the attack on October 14.

The court heard he had been drinking and was also heard talking about the anniversary of his father's death.

The boy along with his young girlfriend and others were also out in Holytown that evening.

The killer left at one point to buy food.

Jack then turned up and started talking to the girl. This included him putting his arm around her.

She appeared upset and on telling her boyfriend what happened, she "formed the view he was annoyed".

The 15-year-old later spotted Jack, who was on his own.

Prosecutor Sheena Fraser said a 13 year-old boy then witnessed the "fatal assault" after the killer told him: "Watch this."

Jack was punched on the head and did not get up. The attacker also aimed a kick at him.

The teenager left the scene but returned and discovered Jack had not moved.

Jack was described as "barely breathing". The boy then told another girl to dial 999.

A local resident meantime tried to give Jack first aid.

The attacker later stated he had "punched an older boy" because he had "tried to kiss and touch his girlfriend".

The boy's father went on to tell police his son had been involved in the assault.

Jack, of nearby Newarthill, ended up on life support but died in hospital two days after being struck.

The cause of death was a head injury.

The teenager was later held by police, but made no comment.

Lady Scott deferred sentencing for reports until August 3 in Edinburgh.