• Hugh Dallas lost his job as head of referee development at the SFA. Picture: SNS
Peter Kearney, director of the Scottish Catholic Media Office, said the e-mail was an example of "deep, wide and vicious anti-Catholic hostility".
Meanwhile, the wider crisis engulfing Scottish referees took a dramatic twist last night with the resignation of Dougie McDonald, the man whose admission that he misled Celtic boss Neil Lennon over his decision to rescind a penalty triggered the current controversy.
Having called last week for Mr Dallas to be sacked if it was proved he forwarded the e-mail that suggested the Pope was a risk to children, Mr Kearney has now said "the bigotry, bile, sectarian undercurrents and innuendos must end".
He said similar e-mails circulated in the weeks leading up to Pope Benedict's visit to Scotland highlighted the level of anti-Catholic feeling in Scotland.
Writing in a Sunday newspaper, he said: "Of the 2,000 or so Catholic priests who have worked in Scotland over the past 25 years, fewer than one in 200 has been convicted of sexual abuse. I am disturbed that in a country where more than 99 per cent of Catholic clergy are innocent of any offence, they can be subjected to so much hate-fuelled scorn. I would challenge critics to provide evidence of any other profession with such an exemplary record."
He claimed anti-Catholic bigotry had existed in Scotland for hundreds of years and urged Scottish Catholics to speak out against it. "It has existed since the Reformation and its viciousness was renewed and deepened when the first Irish migrants arrived a century and a half ago," Mr Kearney wrote.
"Our grandparents and even our parents suffered intolerance and persecution. We will not tolerate it. We will not laugh it off - because there is no funny side."
Reports suggest Mr Dallas, who left his post as head of referee development on Friday, and four other staff members who have also been disciplined are considering suing the SFA for unfair dismissal. The other staff are reported to be Craig Levein's secretary Amanda Macdonald, mailroom boss Bob Bryan, Marco McIntyre from football development and Tim Berridge, an audio visual technician.
The SFA said it had not yet received any appeals.
Its president, George Peat, told The Scotsman affected staff members had five days to appeal the decision. "I saw the four names in the paper today, but I honestly don't know whether they are involved or not," he said."I've tried to stay out of it. If anyone has a grievance or wants to appeal, it'll come to me. I deliberately didn't ask about the identities of the staff so I couldn't be accused of getting involved at this stage."
SFA chief executive Stewart Regan also refused to confirm the names of the staff members who had left.
In response to Mr Kearney's comments, he said: "This was not about anti-Catholicism, in my view. It's about appropriate use of our e-mail and internet, and a decision was taken in relation to abuse of that policy."
Mr Regan has been in post for only six weeks, having recently moved from Yorkshire County Cricket, and said he could not comment on allegations that sectarianism was rife in Scotland or in Scottish football.
He said tackling sectarianism was not the responsibility of the SFA. "We're a football organisation and our job is to deal with football issues," he said.
Mr Regan launched his investigation after reports of the e-mail emerged earlier this month.
The e-mail apparently included a photograph showing a road sign featuring an adult and child with a doctored message below referring to the Pope's visit.
Last Wednesday, Mr Kearney wrote to Mr Regan, suggesting Mr Dallas should be sacked if it was proved he had sent the "gratuitously insulting" e-mail.