The resignation of Britain's most senior Catholic cleric is the biggest crisis for the church in the country for around 450 years, a leading historian has said.
Cardinal Keith O'Brien, Archbishop of St Andrews and Edinburgh, stepped down on Monday, a day after the Observer newspaper reported that three priests and a former priest had complained about him to the Vatican over alleged "inappropriate" behaviour stretching back 30 years.
A spokesman for the Scottish Catholic Media Office (SCMO) said the allegations were "anonymous and non specific" and the 74-year-old cardinal is contesting them and taking legal advice.
Cardinal O'Brien tendered his resignation to the Vatican in November, citing age and "indifferent health", and he had been expected to step down next month when he turns 75, but his resignation now takes immediate effect.
It leaves the Catholic Church in Britain with no vote in the forthcoming conclave to elect a successor to Pope Benedict XVI.
Speaking to STV News, Professor Tom Devine, a leading historian at the University of Edinburgh, said: "It's possibly, in terms of the internal history of the church, the biggest crisis in the history of Scottish Catholicism since the reformation.
"The Catholic Church has always been subject to, for the last several hundred years in Scotland, a range of tribulations, not least the reformation itself. But this is different because this crisis has come from the heart and soul of the church, it's not been through external forces.
"Catholics across Scotland will be hurting and the cardinal himself must be hurting above all, but I think we must bear in mind in the broader perspective that they belong to a church of 1.2 billion people worldwide which has proven resilient for 2000 years."
Cardinal O'Brien, who has been Archbishop of St Andrews and Edinburgh since 1985, was created a cardinal by Pope John Paul II in 2003 and became prominent for his colourful and strongly-voiced defence of conservative Catholic teaching.
In a statement issued by the SCMO on Monday, Cardinal O'Brien said: "I have valued the opportunity of serving the people of Scotland and overseas in various ways since becoming a priest. Looking back over my years of ministry, for any good I have been able to do, I thank God. For any failures, I apologise to all whom I have offended."