SINGAPORE - The presence of young families, including a child in a pram, failed to deter a man from wielding a chopper and attacking a retiree outside a supermarket, causing a deep cut to the victim's forearm which led to permanent impairment.

The public attack caused "general chaos" among terrified onlookers and Deputy Public Prosecutor Ng Jun Chong said it was "fortuitous" that no passers-by were hurt in the incident.

The attacker, Tan Kok Ann, 58, who is jobless, was jailed for 4½ years on Friday (March 1) after pleading guilty to using a weapon to cause grievous hurt to Mr Tan Beng Yian, 69.

He was also ordered to compensate Mr Tan $1,149.86, failing which he will have to spend an additional week behind bars.

DPP Ng told the court that Tan Kok Ann and Mr Tan were neighbourhood acquaintances who had been feuding since 2017 after a physical altercation that arose following a petty argument.

Court documents did not reveal details about this earlier incident.

On Feb 20 last year, Tan Kok Ann wanted to pass the chopper to his mother's maid and was carrying the weapon inside a plastic bag when he spotted Mr Tan walking outside a supermarket at Block 114 Aljunied Avenue 2 at around 7pm.

DPP Ng said: "Still angry from their earlier arguments, the accused walked towards the victim, and when he was about an arm's length away from the victim, he suddenly swung the chopper, still wrapped in newspaper and the plastic bag, at the victim repeatedly.

"The victim raised his right forearm to block the attack and suffered a deep cut on the right forearm area, which bled profusely."

Tan Kok Ann left the scene and police arrested him soon after.

Officers also seized the chopper, which had a 19cm-long blade.

An ambulance took Mr Tan to Tan Tock Seng Hospital and during surgery, the medical team found that his right forearm bone had completely fractured.

His nerves were also damaged, the court heard.

The retiree was given a month's hospitalisation leave until March 20 last year.

Findings later revealed that his fingers are now permanently impaired.

DPP Ng added: "In particular, he was noted to have numbness and stiffness of his fingers, and consequently, he does suffer from permanent disability."

Offenders who cause grievous hurt to their victims by using a weapon can be jailed for up to 15 years and fined or caned. Tan Kok Ann cannot be caned, as he is over 50 years old.