A former Orthodox priest and archbishop has been sentenced to eight months in jail for sexually assaulting an altar boy in Winnipeg during the 1980s.

A Manitoba judge handed down the decision Wednesday morning against Seraphim Kenneth Storheim, 68, calling his conduct "deplorable and a gross breach of trust" and saying the lasting effects of the crime are serious.

Storheim appeared emotionless for much of the hearing, but about a dozen of his supporters who showed up to court were visibly shaken.

Almost immediately, Storheim's lawyer, Jeff Gindin, said his client is appealing the decision.

"There will be plenty" of grounds for appeal, Gindin said.

"Essentially we feel [Court of Queen's Bench Justice Christopher Mainella] analyzed credibility with errors all the way through."

Ginden said Storheim will try to get bail on Thursday.

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Sentencing submissions by the Crown and defence were made last month but Court of Queen's Bench Justice Christopher Mainella reserved his decision until today to go over the lengthy submissions.

The Crown had been seeking a 12-month jail sentence while the defence wanted for a conditional sentence with no jail time.

Storheim had been accused of sexually assaulting two pre-teen brothers in 1985. He had faced two counts — one for each boy.

Earlier this year, he was found guilty in one case but not the other.

The brothers, now in their 30s, testified during the trial that they lived with Storheim in Winnipeg briefly, on separate occasions, when they were altar boys in 1985. He was a priest at the time.

One of the brothers testified that he was made to fondle Storheim, who touched him inappropriately as well.

Storheim denied anything inappropriate took place. He told court that he was telling the boy about puberty based on some Biblical teachings.

The judge rejected Storheim's version of events.

Mainella said one brother was clear in his testimony, while the other had memory and mental illness problems.

At the time of the offence, Storheim was a priest in the Orthodox Church in America. He later rose to archbishop — the church's highest-ranking cleric in Canada.

Storheim was arrested in 2010 after the former altar boys went to police with their complaints. He was placed on leave and then made to retire following his conviction.