Warrnambool police Sergeant Chris Moloney said an unknown Warrnambool offender had ignited a bedroom curtain after a window was left open and towels were also lit in the backyard.

The curtain fire was extinguished by an occupant using a bucket and water.

"That was the 12th fire at the same property since January 31 this year," Sergeant Moloney said.

"Previous fires have been in the backyard and front bushes and caused minor damage. The behaviour appears to be escalating," he said.

"The latest fire caused minor property damage but there was potential for much more damage to be caused. The blaze is being investigated by Warrnambool police Crime Investigation Unit detectives," he said.

It is understood the family who lives in the home is considering its options with the assistance of Aboriginal housing officers.