SINGAPORE - Two surveyors who accepted bribes to misreport the theft of gas oil as part of a massive heist to steal oil from Shell's manufacturing site on Pulau Bukom have been jailed.

With their help, multiple incidents of gas oil theft worth up to $2.5 million went undetected between 2016 and 2017.

The pair showed up separately in court on Monday (Aug 29) and pleaded guilty to corruption.

A. Duraisamy, 60, was jailed for 10 months and fined $42,870.60. He will remain in jail for an additional seven weeks as he is unable to pay the fine.

Lee Been Lian, 58, was jailed for two months and fined $6,795. He will also remain in jail for 19 more days as the fine was not paid.

At least 26 people have been hauled to court over this conspiracy, which was first noticed by Shell in 2015 when it observed significant unidentified oil loss at Pulau Bukom.

The court heard that Duraisamy and Lee worked for firms that helped to inspect the quantity of cargo, such as gas oil, supplied to vessels in Singapore by Shell.

Once the inspections were done, the surveyors would submit reports on the amount of cargo loaded onto the vessels and hand them to their employer and Shell, said Deputy Public Prosecutor Norman Yew.

The duo were drawn into a conspiracy to steal gas oil from Shell's largest production plant in the Asia-Pacific region on Pulau Bukom.

The heist was said to have been masterminded by former Shell employees Juandi Pungot, Muzaffar Ali Khan Muhamad Akram and Richard Goh Chee Keong, who bribed surveyors to hide the theft of oil.

Juandi was on March 31 jailed for 29 years for his role in masterminding the misappropriation of more than 200,000 tonnes of gas oil worth $128 million. This was one of the longest prison sentences for a commercial crime.

Muzaffar's and Goh's cases are still before the courts.

Between 2013 and 2017, Duraisamy accepted around $25,000 in bribes from the masterminds to turn a blind eye to the theft of oil while he was employed by Intertek Testing Services and Inspectorate Singapore.

He worked with colleagues, who have also been hauled to court, to conceal the theft of oil and split the bribe money with them.

With Duraisamy's help, three incidents of misappropriation of Shell gas oil worth US$1.8 million (S$2.5 million) went undetected in 2016 and 2017.

In 2017, Lee was similarly roped into the conspiracy when his colleague Erwin Suhardi Jamaluddin - who was jailed in July this year - offered him a cut of the bribe money to misreport the theft of oil.

Lee received US$5,000 through Erwin, and his actions helped to conceal an incident of gas oil theft worth US$1.2 million.

The maximum penalty for corruption is a $100,000 fine and five years in jail.