A Church of England bishop has added her voice to growing calls for the archbishop of Canterbury to resign over his failure to pursue a sadistic abuser of children when allegations were brought to his attention.

Helen-Ann Hartley, the bishop of Newcastle, said Justin Welby’s position was untenable and he should quit. A line needed to be drawn, she added.

“I think that it’s very hard for the church, as the national, established church, to continue to have a moral voice in any way, shape or form in our nation, when we cannot get our own house in order with regard to something as critically important [as abuse],” Hartley told the BBC.

Andrew Morse, who was beaten by John Smyth as a teenager, also called on Welby to resign, saying it would send a powerful personal and public message that the church would no longer cover up abuse.

“His resignation would be a positive step in a very bleak situation that has existed ever since Smyth started beating me and my friends more than 40 years ago,” he told the Guardian.

Welby and his advisers at Lambeth Palace, the archbishop’s headquarters, had prioritised the reputation of the church over and above the plight of Smyth’s victims and their “inactivity that was tantamount to a cover-up” had allowed Smyth to continue to abuse with impunity, he said.

“There hasn’t been a day that I haven’t felt the reverberations [of the abuse],” Morse added. “I still lie awake at night trying to process what happened. I have only survived because of love, support and professional help.

“I’d hope Welby would see this as an opportunity to draw a line, to say enough is enough. I feel his conscience must be telling him this.”

Members of the Church of England’s ruling body, the General Synod, have launched a petition calling on Welby to quit, “given his role in allowing abuse to continue”. By 5pm on Monday the petition had 5,000 signatures.

Robert Thompson, who set up the petition, said the church’s handling of the Smyth abuse case was of concern to people “right across the theological spectrum” of the C of E.

Thompson, a campaigner for LGBT equality within the church, had joined forces with conservative clergy to call for Welby’s resignation.

“This is a buildup of multiple, serial reports on cases of abuse and how the church has dealt with them. There is real disgust that we have had report after report, apology after apology, and nothing has changed.

“It’s not just about Welby, it’s about the culture in the church. But Welby has lost the confidence of a significant number of clergy in the C of E. The bishop of Newcastle represents the views of other bishops who don’t want to speak out. I don’t think Welby can survive this.”

The archbishop had “lost the confidence of clergy”, Giles Fraser, a London vicar, told BBC Radio 4’s Today programme. “This needs to be our watershed moment in the church, where we look at the culture of deference, the way in which many of our senior leadership rally to defend each other.”

Welby said last week he had considered resigning over his “shameful” decision not to act remorselessly to deal with reports of abuse by Smyth, a powerful and charismatic barrister who died in 2018, when he was informed of them in 2013.

Lambeth Palace said in a statement on Monday that Welby had “apologised profoundly both for his own failures and omissions, and for the wickedness, concealment and abuse by the church more widely” but “does not intend to resign”.

Pressure on Welby has been intensifying since the publication last week of a damning report on the church’s cover-up of Smyth’s abuse in the UK in the late 1970s and early 1980s, and later in Zimbabwe and South Africa. About 130 boys are believed to have been victims.

The report by Keith Makin described the abuse as “prolific, brutal and horrific”. The C of E “knew at the highest level about the abuse” but its response was “wholly ineffective and amounted to a cover-up”.

Welby and other senior figures in the C of E were told of allegations that Smyth had abused dozens of boys who attended evangelical Christian holiday camps run by the Iwerne Trust, beating them viciously in his garden shed. Many of the boys were pupils at Winchester college, one of the UK’s top public schools.

Welby had volunteered at the holiday camps in the late 1970s but has said he was unaware of the allegations at the time. The Makin report said Welby was informed of the abuse allegations in 2013 but failed to take action, and that it was “unlikely” he would have been unaware of rumours surrounding Smyth when he was volunteering at the camps.

“[Welby] may not have known of the extreme seriousness of the abuse but it is most probable that he would have had at least a level of knowledge that John Smyth was of some concern,” it said.

After Channel 4 News exposed Smyth’s abuse in 2017, Welby told the programme he had “no idea that there was anything as horrific as this going on … I had no suspicions at all”.

Calls for Welby to resign are being partly driven by clergy who are frequent critics of the archbishop over his leadership of the C of E, though they may gather wider momentum over the coming days.

Welby is expected to announce his retirement in the coming weeks or months. Bishops in the C of E are required to stand down at the age of 70. Welby will hit that milestone in January 2026 but bishops generally give long notice of impending retirement as the appointment process is notoriously slow.

Lambeth Palace said: “The archbishop reiterates his horror at the scale of John Smyth’s egregious abuse, as reflected in his public apology. He has apologised profoundly both for his own failures and omissions, and for the wickedness, concealment and abuse by the church more widely.

“As he has said, he had no awareness or suspicion of the allegations before he was told in 2013 – and therefore having reflected, he does not intend to resign.”