Half a hectare of grassland was burned at Blighty on Tuesday.
RFS Mid-Murray district assistant Terry Campbell said there are two possible causes for the blaze which started at the corner of the Riverina Highway and Blighty School Rd.
He said it was either a discarded cigarette butt, or a spark from a hot car exhaust in the grass.
The Deniliquin brigade was called to battle the blaze about 12.30pm, and were able to have it contained quickly.
Firefighters remained on site until just after 3pm to ensure slow burning logs did not cause reignition.