"Pickering escaped, the church didn't assist in bringing him to justice, when victims turned to the church they offered them no support, and then he died," said Mike, who was abused almost 50 years ago when he was an altar boy at St Mary's in St Kilda East, which someone attempted to set alight early Monday.

"If a victim is lighting these fires, it's a symptom of anger. But you certainly don't want to encourage this as a way of dealing with anger."

Christian holy days such as Easter could trigger strong emotions within some victims, Mike said, but he hoped that the Royal Commission into Institutional Child Sexual Abuse would provide some justice.

It remains unclear whether a sex abuse victim, or victims, are responsible for the three fires at churches in Brighton, St Kilda East and Dandenong since Sunday.

But Mike said it was too much of a coincidence that the three churches all had notorious pasts.

Two separate fires were lit at St Mary's Church on Foster Street in Dandenong - one in the main church at the altar and the other in a storage room containing cloaks - about 2am on Wednesday, causing $250,000 damage.

It took firefighters 90 minutes to gain control of the blaze.

Police are investigating whether the fire is linked to two other suspicious fires at Catholic churches in Brighton and St Kilda East on Monday.

Fire destroyed the 123-year-old St James Church in Brighton on Monday morning, while a separate blaze started near a door at St Mary's in St Kilda East caused little damage.

Both churches are linked to Ronald Dennis Pickering, who  abused boys at several Melbourne parishes between 1958 and 1993, when he fled to his native Britain. He died there in 2012, having never been charged.

Convicted paedophile priest Kevin O'Donnell abused dozens of young boys and girls at St Mary's Church in Dandenong between 1958 and 1986.

O'Donnell retired in 1992. In 1995, aged 78, he pleaded guilty to indecently assaulting 10 boys and two girls, aged between eight and 15, and spent 15 months in jail. He was freed in 1996, and died in 1997.

There have been other arson attacks linked to clergy abuse.

It is believed at least four Catholic churches in Melbourne, Collingwood, Kinglake and Chelsea, including some linked to paedophile priests, have been targeted by arsonists in the past 20 years.

O'Donnell had served at the Chelsea church as assistant priest from 1944 to 1949.

Regional Bishop for the South, Peter Elliott, told radio station 3AW he did not believe there was a link between the fires, but 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 it was a victim of sexual abuse.

"There have been fires in the recent past that haven't had these links that are being alleged at the moment, not even the link of historical buildings. I don't see any pattern so far, except a very disturbed person," he said.

Detective Senior Constable Nic Hayes from Dandenong police said it was too early to confirm any links between the Wednesday fire and the two earlier fires. He appealed for any witnesses to the Dandenong fire to come forward.

A police spokeswoman confirmed the St Mary's fire in St Kilda East had been deemed suspicious, but said the cause of the fire at St James was yet to be determined. St Kilda detectives are investigating both fires.

Chris McIsaac, the founder of Broken Rites, a group established to help victims of church-related sexual assault, said dozens of churches around Victoria could be linked to sexual abuse. She said it was possible an arsonist was simply targeting churches, rather than those linked to paedophile Catholic priests.

The Archdiocese has not yet decided whether to increase security at other churches linked to the priests. According to Broken Rites, Pickering also served at St Theresa's in Essendon, Sacred Heart in Warburton, and St Peter's in Clayton. O'Donnell, who offended during about 40 years in the clergy, also served at South Melbourne, Balaclava, Seymour and East Melbourne (St John the Evangelist parish), Hastings and Oakleigh.

Arrangements had been made for Easter church services at the three churches, said a spokesman for the Catholic Archdiocese. Easter services at St Mary's in Dandenong have been moved to the nearby school, also called St Mary's.

St James services have also been moved to a nearby school, Star of the Sea. Services at St Mary's in St Kilda East will continue as scheduled.