Eleven men were charged in a Singapore court Tuesday over their part in an alleged oil theft at Shell's biggest refinery, court documents showed.

Royal Dutch Shell, which first reported the heist to authorities last August, said in a news release that the 17 arrests included "a limited number of Shell employees" from the Bukom facility. While nine Singaporeans were charged over the theft of oil, two Vietnamese nationals were charged with receiving stolen goods.

Police said six people who had not been charged so far were still under investigation. Officers also seized millions of dollars in cash and a small tanker in connection with the case.

Crucial oil trade

Bukom is the largest wholly owned Shell refinery in the world in terms of crude distillation capacity.

Shipping and oil refining have contributed significantly to Singapore's rising wealth over the past decades.

The Southeast Asia city-state is one of the world's most important trading hubs, with most of the Middle East's crude oil passing through Singapore before being delivered to consumers in China, Japan and South Korea.

hg/jd (Reuters, AFP, AP)