More than 25 firefighters were required to battle a suspicious blaze at a Keilor Downs property last night.

Firefighters were called to a single-storey property in Sobar Street about 8.16pm and found the property engulfed by fire.

Equipped with breathing apparatus, firefighters entered the property to conduct a search after reports that an occupant may have been inside, however the building was clear.

The fire was brought under control in 20 minutes, but the building suffered extensive damage.

Its structural integrity will now be examined the a building surveyor, while the scene has been handed over to Victoria Police for investigation.