An assistant bishop is set to become the most senior Anglican in Australia to be defrocked after a church committee on Tuesday found he took no action when he was told a priest had sexually abused a child.

Assistant Bishop Richard Appleby has 28 days to appeal the decision by the Professional Standards Board of the Anglican Diocese of Newcastle to strip him of all roles in the church other than parishioner.

Appleby's lawyer, Peter Skinner, said he had yet to receive instructions from his 78-year-old client on whether he would appeal.

The church investigation follows criticisms of Appleby in the government-commissioned Royal Commission into Institutional Responses to Child Sexual Abuse, which made its final report in December 2017.

Australia's longest-running royal commission — which is the country's highest form of inquiry — had been investigating since 2012 how institutions responded to sexual abuse of children in Australia over 90 years. The inquiry heard the testimonies of more than 8,000 survivors of child sex abuse.

The board found Appleby, as assistant bishop in Newcastle in 1984, did nothing after he was told by a victim, identified as CKA, he had been sexually abused by priest George Parker. Parker remained a priest in Newcastle until 1996.

"I am satisfied that because of the conduct found, the respondent (Appleby) is unfit permanently to hold any office," board president Colin Elliott wrote.

Elliott said a "cover-up culture" prevailed in Newcastle at the time.

Parker died in 2017 at age 79, three weeks after he was charged with 24 child sex offenses against two young boys in the 1970s.

Appleby has denied being told about Parker's crimes.

Newcastle is in the Hunter Valley region of New South Wales state north of Sydney which has become notorious for pedophile clerics.

In May last year, former Adelaide Archbishop Philip Wilson became the most senior Roman Catholic ever convicted of covering up child sex abuse. But the conviction was quashed on appeal in December.

The 68-year-old cleric had been accused of concealing the sexual abuse of two altar boys by a pedophile priest in the Maitland-Newcastle diocese in the 1970s.

Wilson had served almost four months of a yearlong home detention sentence at his sister's house outside Newcastle when his conviction was overturned.

Appleby does not face criminal charges.

CKA shed tears after learning of the board's decision.

"It's significant that the church as a body is prepared to take that action against him," CKA told Australian Broadcasting Corp.

"Today's findings couldn't have been stronger about the culture of the church that existed at that time, and hopefully this is an end of that," CKA added.