"This planned maintenance started on Feb. 20 and is expected to last several weeks," the company said in a statement.

Exxon Mobil operates two refineries in Singapore. The Jurong refinery has a crude-processing capacity of 302,000 barrels per day (bpd), while the other refinery on Jurong Island can process 290,000 bpd of crude oil.

(Reporting by Seng Li Peng, Writing by Florence Tan, Editing by Sherry Jacob-Phillips)