A "SIGNIFICANT" suspicious fire at a derelict Deakin Avenue building known to be frequented by squatters could have turned to tragedy had anyone been caught inside, according to police.

The two-storey former Tschirpig Bakery and RSPCA Op-Shop site on the corner of Boyden Street was "fully involved" when Fire Rescue Victoria crews were called just before 9.30pm Wednesday.

Aside from the fro...