A Vietnamese tanker captain has been jailed for five and a half years for his part in a plot to steal $150m of fuel from a Shell refinery in Singapore.

Doan Xuan Than became the second person to be sentence in a sweeping case that has seen eleven former Shell employees and several others have been charged.

The scam took place at Shell Eastern Petroleum’s Pulau Bukom refinery in 2016 and 2017. Prosecutors described it as misappropriation on an “unprecedented scale”.

Doan received about $5.7m of stolen marine gasoil, the Malay Mail reported.

The 47-year-old tanker master pleaded guilty to dishonestly receiving more than 8,000 tonnes of stolen gasoil on 10 occasions.

He worked with three other men, who remain at large, the report said.

Doan claimed that he earned between $70,000 and $90,000 in total up until his arrest.

He was employed by Prime Shipping Corp from 2012. He captained the 12,000-dwt Vietnamese-owned Prime South (built 2009), the ship used in the fuel scheme.

Another Vietnamese man, 48-year-old Pham Van Ban, was set to plead guilty alongside Doan in Singapore on Thursday to one charge of conspiring to receive $500,000 worth of gasoil. But his case was adjourned to next month.

Chief officer jailed

In July, Prime South's chief officer was jailed for two and a half years. Dang Van Hanh, 38, was the first person to plead guilty.

He was initially assigned to another vessel, and when transferred to Prime South, he was informed by its outgoing chief officer that the ship had received illegal cargo from Shell's Pulau Bukom refinery on multiple occasions for extra money, CNA reported.

The court heard that the crew began loading legitimately bought oil.

The next day, the captain asked Dang to change the hose connection, switching it with two Shell employees to transfer stolen gasoil to the three remaining tanks.

Shortly after this, police officers boarded the ship.

Dang later said that he was paid between $1,000 and $2,000.