The Catholic Church is bracing for possible arson attacks on Melbourne parishes linked to paedophile priests, 12 months after vandals torched three suburban churches.

The Catholic Archdiocese of Melbourne has told its parishes to be vigilant following an attempted arson attack on St Bede's Church in Balwyn North earlier this month. An intruder broke into the church and poured accelerant onto the altar, but is believed to have fled before lighting the fire because an alarm went off.

Father Ronald Pickering [L] with choir.

In an email to the 214 churches in the Melbourne Archdiocese, vicar-general Monsignor Greg Bennet warned of the risk of arson, saying the Balwyn church's alarm system was all that foiled "what would have been another catastrophic fire". It coincides with the one-year anniversary of three as-yet-unsolved fires at churches where paedophile priests worked.