The 120 000 barrels-per-day (bpd) refinery in Durban is shut for routine maintenance from July 30 to September 9 with all units affected, the spokesperson added.
"Imports have and will be used to make up any shortfall in products," the spokesperson said, without elaborating further.
The refiner, which is majority-owned by Malaysian state oil firm Petronas, was already in the spot market seeking 36 000 tonnes of diesel for delivery in October, which helped to support cash premiums for the grade, traders said.