UPDATE, Monday, 1.25pm:
Police are investigating the cause of a fourth fire at Wool Wool Road, north of Colac, during the past week.
The latest incident was reported overnight Sunday when a curtain in a home was damaged.
That followed fires in a haystack on February 14 and February 15. The second fire destroyed the stack of small bales valued at thousands of dollars.
Last week there was also a fire in a nearby paddock.
Overnight Sunday another fire was believed to be deliberately lit in a home, causing minor damage.
It's understood there have been about eight fires in the same area during the past 12 months.
Detective Senior Constable Stuart Sims, of the Colac police crime investigation unit, requested anyone with information about the fires contact the Colac police station on 5200 0000 or Crime Stoppers on 1800 333 000.
February 15: Colac police investigators are looking into the cause of two fires in a haystack north of the city which destroyed hundreds of small bales.
Detective Sergeant Brendan Butland, of the Colac police crime investigation unit, said emergency services were called to a fire in a haystack on Wool Wool Road at Wool Wool about 1.40am Sunday.
He said Sunday's fire was relatively small and Country Fire Authority volunteers were able to bring the blaze involving small square bales under control.
"Then there was another fire at about 4.30am Monday at the same rural property hayshed," he said.
"That fire took hold and the haystack was destroyed. The CFA pulled it apart but none of the bales have been saved."
Detective Sergeant Butland said Colac CIU members and a CFA investigator were looking into the cause of the fires.
"It's an isolated property. The nearest neighbour would be about one kilometre away," he said.
"Due to the COVID restrictions there has been very little traffic on the roads and we are asking that anyone who saw a vehicle on the roads in that area, at those times immediately contact the Colac police station (5230 0000) or Crime Stoppers on 1800 333 000."
The value of the damage is expected to run into thousands of dollars with small square bales valued at up to $8 each.
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