A deliveryman who slashed a fellow worker with a chopper was jailed for 18 months on Tuesday.

Chinese national Chen Ningke, 38, admitted to grievously hurting lighting technician Du Kang, 27, who is also from China, causing him to suffer multiple injuries at SJ Lite at Ubi Link on Dec 12 last year. Both men shared a room at the company premises.

That evening, the victim was completing some work at the common work station when Chen came and borrowed his phone. He walked away, pretending to make a telephone call.

When the victim turned back to face the common work station, Chen whipped out a chopper and assaulted him from behind.

He hacked the back of the victim's head, slashed his face and continued attacking the victim even after he had fallen off his chair.

A colleague heard the commotion and rushed to help the victim. He armed himself with a chair to fend off Chen's blows. He managed to persuade Chen to stop the assault on the victim.

The victim suffered cuts over the back of his scalp, both arms and a broken left finger.

Chen, who was spared caning, was found to be suffering from a psychotic illness likely to be schizophrenia at the time of the offence, said his lawyer Louis Lim.

A government psychiatrist stated that Chen was experiencing auditory hallucinations and harboured persecutory delusions.

Chen could have been jailed for up to 10 years, fined or caned.