SINGAPORE - A 21-year-old man was placed on 15 months' probation on Wednesday for punching another person last year and causing his nose to fracture.

Niap Boon Kang, then a full-time national serviceman, pleaded guilty to causing grievous hurt to Mr Claudius Keng Sing Yang, 23, at the entrance of the Rehabilitation Centre of Alexandra Hospital on Sept 5 last year.

Niap, who suffers from anti-social personality disorder and attention deficit hyperactivity disorder, had been admitted to the nearby Singapore Armed Forces (SAF) Ward the previous day as a day patient.

The court heard that Mr Keng, then 21, had given chase and tried to calm Niap down after he created a scene in the ward's lobby area and tried to run away, shouting that he needed to see a doctor immediately.

Mr Keng told Niap that no one was preventing him from seeing the doctor, but Niap, then 19, punched him and continued throwing punches despite Mr Keng's attempt to shield himself. Niap continued the assault until the two were separated by other people.

It is understood that Niap was later discharged from service due to his condition, and eventually apologised and paid compensation to his victim.

He could have been jailed for up to two years and fined up to $5,000.