A collection of small fires that stretched for 300 metres near Woolsthorpe at the weekend were not the work of arsonists, police say.
Koroit police Sergeant Pat Day said emergency services were called to up to 15 small spot fires on the Woolsthorpe-Heywood Road at Hawkesdale about 2.45pm on Saturday.
He said the fires stretched for about 300 metres on the north side of the road, which was closed to vehicles travelling east for about 30 minutes.
He said there was also a small spot fire on the Warrnambool-Caramut Road, south of Woolsthorpe.
"CFA worked quickly to put out the fires which we initially thought were the work of arsonists," Sergeant Day said.
"We set up crime scenes and two investigators travelled from Ararat. After close inspection they realised the fires were started from an exhaust system of a vehicle.
"The vehicle must have been dropping pieces of hot metal onto the road surface which then rolled into the grass and sparked the multiple fires.
"Due to the nature of the individual fires, there were fears it was an arson attack but the incidents are no longer being treated as suspicious."
Sergeant Day said the fire at Warrnambool-Caramut Road spread into a person's paddock and burnt a fence.
"CFA worked pretty quickly to bring the fires under control within 30 minutes to 40 minutes," he said.
"It was a pretty good result in the end. With half of the country on fire, we don't want people to be worried about an arson bug."
Sergeant Day said the owner of the vehicle that caused the fires was unknown.
"They wouldn't have even known what happened," he said.
"It was not a deliberate act but it shows the importance of ensuring your vehicle is road-worthy."
Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.