Wood piles at the Maryvale paper mill were still burning on Monday morning after an overnight ember attack from the Hernes Oak fire.
The Latrobe Valley mill, north of Morwell, is likely to remain closed for up to two days.
On Sunday afternoon CFA firefighters and staff began putting out small fires in the mill, sparked by flying embers.
The mill's owner, Australian Paper, said the fires had damaged electrical cables and a conveyor belt.
Spokesman Mark Nelson said employees who could make it to work were helping with the firefighting effort.
"We've got the majority of our people in. There's a bit of difficulty getting in with road closures but we'll continue to have our people work."
The mill produces paper for photocopying and packaging.
At 8.35am on Monday the CFA advised that the Hernes Oak fire had subsided, but the 2600 hectare blaze was still not under control.
An unknown amount of homes and an archery range in nearby Morwell have already been lost to the fire.