A devastating shed fire between Moama and Mathoura, which has destroyed about $1 million worth of hay, is under investigation.
Moama RFS was called to a property on the Cobb Hwy near Stud Farm Lane about 5am where firefighters found the hayshed fully engulfed.
RFS Mid-Murray duty officer Terry Campbell said the destruction of 5500 hay bales, equating to about 3300 tonnes, in the 14-bay shed was a devastating loss for the farmer.
"It's hard to say what caused it. It is under investigation," he said.
"Spontaneous combustion can occur at any moment when a bit of water gets it in them, however this hay has been stored and dried since November which makes it strange."
A fire investigator from Deniliquin will examine the scene this morning to determine the cause.
"The fire will burn for at least a few days but will be monitored through the day by the landowner," Mr Campbell said.
The fire is contained so there is no risk of it spreading and there is no danger to the public.
However, people are being advised smoke will be visible for a number of days.