Police in Melbourne are investigating suspected arsons at three churches with historic links to abusive priests.
Fire destroyed the 123-year-old St James Church in Brighton in late March.
And fires at St Mary’s Church in Dandenong caused A$250,000 worth of damage.
A separate blaze started near a door at St Mary’s in St Kilda East caused little damage.
Bishop Peter Elliott said the Catholic archdiocese would increase security at local churches.
Bishop Elliott suggested an arsonist with a “very disturbed mind” was responsible for the fires, but doubted the instigator was a victim of sexual abuse.
A spokesperson for a victims’ support group said it was possible an arsonist was simply targeting churches generally, rather than those linked to abuse.