SINGAPORE - A 62-year-old bus driver stopped the vehicle and locked its doors after he noticed two men drinking in it.

Upon realising this, Aziz Khan Sher Khan held the driver down as Ahmad Robinson beat him up, fracturing the man's nasal bone.

For his part in the assault, Aziz, 61, was sentenced to 10 months' jail in court on Wednesday (Dec 29). He was also given an additional enhanced sentence of 24 days for committing the offence while out on remission.

The Singaporean pleaded guilty to one count of voluntarily causing grievous hurt.

A warrant of arrest was issued for Ahmad, 70, on Dec 1 after he failed to turn up in court, and he remains at large.

According to court documents, Aziz and Ahmad, having already drunk alcohol, boarded the Go-Ahead Singapore bus at the stop at Selarang Halfway House at about 10.35am on Nov 2.

They sat at the front of the bus, and the driver told them to put on their masks properly when he noticed them drinking beer.

He reported the matter to Go-Ahead Singapore's control room and was advised to stop and lock the doors as a police report had been made.

The driver then locked the doors and stopped the bus along Loyang Avenue.

Angered, Aziz and Ahmad confronted the driver and shouted at him to open the door, but he refused.

The duo approached the driver and spoke to him in a threatening manner. Aziz then grabbed the driver by his shirt before returning to his seat.

Ahmad also hurled vulgarities at the driver and grabbed his shirt, as a tussle broke out.

The driver took out his mobile phone to try to make a call but Ahmad hit it out of his hand. Aziz joined in and restrained the driver.

Deputy Public Prosecutor Emily Koh said: "At this point in time, while (Aziz) was holding on to the victim's left arm to restrain him, (Ahmad) climbed over the bus driver's cabin door and went into the driver's cabin area."

Ahmad then slapped, punched and hit the victim's head and face multiple times, as well as his nose area. He also kicked him multiple times.

The two men fled after the bus doors were accidentally opened.

Another bus passenger called the police.

An X-ray showed that the bus driver had sustained a nasal fracture. He was granted hospitalisation leave for seven days.

DPP Koh asked for a jail sentence of 12 to 18 months, with an enhanced sentence of 24 days. She said the attack was on a public transport worker, was one-sided and a result of self-induced intoxication.

In meting out his sentence to Aziz, District Judge Lim Wen Juin said the driver was vulnerable during the assault as he was trapped on the bus.

But he acknowledged that Aziz had a reduced culpability compared to Ahmad as he had mainly been involved in restraining the victim.

Aziz's sentence was backdated to Nov 3.