The Tongaat-Hulett Group's head office was not affected by the fire, which broke out in the North Coast town of Tongaat on Monday.
Part of a small agricultural personnel office complex belonging to the Tongaat-Hulett Sugar Division at Klipfontein, near the Group head office Amanzimyama, was damaged.
The fire damaged a large lecture room, the clinic, security office and storerooms.
Forensic investigations are underway and at this stage the cause of the fire is unknown. Early estimates of the damage costs are between R1 million and R2 million.
There were no injuries.