SINGAPORE - A bus depot foreman cheated his employer SBS Transit out of more than $200,000 in a scam involving payments for technical work.

Ong Sang Fei, 47, would claim that the work carried out on buses was done by Azech Engineering, a company set up by his alleged accomplice Koh Dawei, 34.

SBS would pay Azech for the work done, when in fact it had been carried out by employees of Venda Engineering and Trading - without their bosses' knowledge.

Ong received an 83 per cent cut of the payments, with the rest going to Koh.

The scam - which ran from 2013 to 2015 - was laid bare on Thursday (April 5) as Ong was jailed for a year after pleading guilty to 20 cheating charges involving more than $66,000.

Another 113 similar charges involving over $145,000 were considered during sentencing.

Deputy Public Prosecutor Sanjiv Vaswani said Ong worked at Soon Lee Bus Depot near Boon Lay Way and reported to workshop manager Zee Chee Wah.

Koh was an operations manager for Venda and reported to its owner, Mr Sim Yew Ying.

SBS buses were maintained at the depot with routine works conducted by SBS' in-house team or Venda. "Ad hoc jobs", however, were referred to a foreman who would obtain quotes from approved contractors. The foreman would then obtain an approval from the workshop manager to award the job to a particular contractor.

DPP Vaswani said that Koh set up Azech in 2013 without his boss's knowledge and agreed with Ong to use Azech to perform ad hoc jobs at the depot.

He added: "Although Azech would issue quotations and invoices in its own name, the jobs would be done by Venda's technicians...Ong would use part of his 83 per cent share to pay Venda's technicians for their work and keep the balance for himself."

Court documents did not say whether Venda technicians were in cahoots with the pair.

Koh and Ong knew that SBS and Venda were unaware of this arrangement and would not condone it if they found out, the court heard.

Ong told Mr Zee the depot could not cope with the volume of work it received and recommended Azech to be SBS' approved contractor.

Investigations revealed that Azech's jobs were later done by one or two of Venda's technicians during their working hours for Venda.

The court heard that according to Mr Sim, the use of Venda's technicians to do other work would cause SBS to suffer a backlog and attract liquidated damages.

DPP Vaswani said: "SBS did levy liquidated damages on Venda because of its backlog. (Mr) Sim also stated that Venda had to pay its technicians overtime."

Court documents did not say how the scam was uncovered. Koh case is pending. No restitution has been made.