The tank is meant for storage of naphtha, a petrochemical cracking feedstock, they said.
Traders said the fire will not have any impact on the market as the company’s production facilities are currently idle.
The company could not be reached for comment.
According to the Singapore Civil Defence Force (SCDF), a fire at an oil tank on Jurong Island was reported to them at about 15:00 Singapore time (07:00 GMT) on Wednesday. Firefighters were deployed to contain the blaze at the site.
Additional reporting by Yeow Pei Lin and Nurluqman Suratman