Pope Benedict XVI is to resign at the end of this month, the Vatican has confirmed, stating that his ailing health means he can no longer meet the challenges the church must face in the modern world.
Citing his "advanced age", the 85-year-old told the Vatican he would resign on February 28, at 8pm as he was "no longer suited" to carrying out the tasks his role demanded. He is the first Pope to resign since 1415.
In an official statement, the Pope said he had "repeatedly examined my conscience before God" but had concluded "that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.
"I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering."
In the statement, he hinted that the challenges of the modern world and the quest for the Catholic church to remain relevant needed to be tackled by a younger, stronger character.
"However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the barque of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me"
He said he was "well aware of the seriousness of this act".
According to Italian news agency ANSA, the announcement was made in person, in Latin, during an "ecclesiastical council discussing the canonisation of the martyrs of Otranto."
The dean of the College of Cardinals, Angelo Sodano, described the Pope's resignation as "a bolt from the blue".
Born Joseph Aloisius Ratzinger, Pope Benedict XVI has been in the post for seven years, taking office at the age of 78, one of the oldest new Popes in history.
He is the first "digital Pope", appearing on Twitter last year as @Pontifex, and racking up almost 1.5m followers.
His last tweet gave no clue to his resignation, but spoke of redemption for sinners.
According to AP, a conclave will elect a new pope before the end of March.
Archbishop Vincent Nichols, president of the Catholic Bishops’ Conference of England and Wales, said the announcement has "shocked and surprised everyone."
"Yet, on reflection, I am sure that many will recognise it to be a decision of great courage and characteristic clarity of mind and action.
"The Holy Father recognises the challenges facing the Church and that “strength of mind and body are necessary” for his tasks of governing the Church and proclaiming the Gospel.
"I salute his courage and his decision.
"I ask people of faith to keep Pope Benedict in their prayers. We Catholics will do so, with great affection and the highest esteem for his ministry as our Holy Father remembering with joy his Visit to the United Kingdom in 2010."
The Archbishop of York John Sentamu called the departing Pope "a great theologian with great spiritual depth."
Pope Gregory XII was the last pope to resign, almost 600 years ago, during the Western Schism when three challengers claimed the papal throne.
The option of a pope to resign is explicitly written into the Code of Canon Law. It says a pope may step down, but stipulates that the decision must be made freely and “duly manifested.”
In 2005, when Pope Benedict succeeded Pope John Paul II, the church was engulfed in the priest child sex abuse scandal and damaging claims that local dioceses were complicit in their cover-up.
Before his election, Cardinal Ratzinger headed the Vatican's Congregation for the Doctrine of the Faith - formerly the Holy Office of the Inquisition. That led to the nickname "God's Rottweiler".