Britain’s most senior Catholic leader, notorious for his anti-gay views, has been reported to the Vatican over historical allegations of inappropriate behaviour involving several male priests dating back 30 years.

The Observer reports three priests and one former priest made the complaint against Cardinal Keith O’Brien, leader of the Scottish Catholic Church.

The four, from the diocese of St Andrews and Edinburgh, have complained to nuncio Antonio Mennini, the Vatican’s ambassador to Britain, and demanded Cardinal O’Brien’s immediate resignation.

A statement from the Scottish Catholic Church said Cardinal O’Brien contested the claims and was taking legal advice.

It is understood that the first allegation against the cardinal dates back to 1980.

The complainant, who is now married, was then a 20-year-old seminarian at St Andrew’s College, Drygrange, Scotland, where Cardinal O’Brien was his “spiritual director”.

Inappropriate conduct is alleged to have taken place with three other priests.

One of the complainants, it is understood, alleges that the cardinal developed an inappropriate relationship with him, resulting in a need for long-term psychological counselling.

The four submitted statements containing their claims to the nuncio’s office the week before Pope Benedict’s resignation on 11 February.

They fear that, if Cardinal O’Brien travels to the forthcoming papal conclave to elect a new pope, the Catholic Church will not fully address their complaints.

“It tends to cover up and protect the system at all costs,” said one of the complainants to the Observer. “The church is beautiful, but it has a dark side and that has to do with accountability. If the system is to be improved, maybe it needs to be dismantled a bit.”

Cardinal O’Brien is the only man in Britain with a say in who succeeds Pope Benedict XVI after he stands down on 28 February.

It is a stunning turn of events for the cardinal.

On Friday, in an interview with BBC Scotland, Cardinal O’Brien said that male priests within the Catholic Church should be able to marry female partners.

He said: “I would be very happy if others had the opportunity of considering whether or not they could or should get married.

“It is a free world and I realise that many priests have found it very difficult to cope with celibacy as they lived out their priesthood and felt the need of a companion, of a woman, to whom they could get married and raise a family of their own.”

Last November, Cardinal O’Brien was named ‘Bigot of the Year’ by a gay rights charity due to his staunch opposition to marriage equality.

In 2012, he stated that same-sex relationships were “harmful to the physical, mental and spiritual wellbeing” and compared equal marriage to slavery and child abuse.

He is due to retire next month.

Meanwhile on Saturday, the Vatican refused to confirm or deny claims of a network of gay prelates operating at its heart, some of whom allegedly were being blackmailed.

Italian daily newspaper La Repubblica published an article last Thursday claiming that Pope Benedict XVI’s decision to resign was in part finalised by a Vatican report showing that the Holy See was affected by outside influences, including a “gay lobby”.