Benedict XVI intends to step down on February 28. The Vatican's statement on the matter said that the decision was the Pontiff's and his alone.
The Vatican said that Benedict's resignation means that the Papacy
will remain vacant pending the naming of his successor, adding that the pope will continue to lead the Catholic World until then.
The Vatican aspires to keep the period between Benedict's resignation and election of successor to be "as brief as possible," the statement said.
Father Lombardi added that the Pontiff will retire to his summer residence, near Rome, before moving to the cloistered residence in the Vatican.
The Vatican plans the stage for a conclave to elect a new pope before the end of March. Benedict will not take part in conclave to elect his successor, Lombardi added.
Who will succeed Pope Benedict XVI? (Photo: AP)
Benedict, 85, is the Holy See's 265th pope. He is the sixth German to serve as pope and the first since the 11th century.
He has led the church during a time in which the church is declining in his native Europe
but expanding in Africa and Latin America.
The pope's resignation announcement reads as follows: "Dear Brothers, I have convoked you to this Consistory, not only for the three canonizations, but also to communicate to you a decision of great importance for the life of the Church.
After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.
First Pope to resign in centuries (Photo: EPA)
"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.
"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 bark 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.
"For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff
will have to be convoked by those whose competence it is."
The statement continues, saying "I thank you most sincerely for all the love and work with which you have supported me in my ministry and I ask pardon for all my defects.
See of Rome from 2005-2013 (Photo: AFP)
"And now, let us entrust the Holy Church to the care of Our Supreme Pastor, Our Lord Jesus Christ,
and implore his holy Mother Mary, so that she may assist the Cardinal Fathers with her maternal solicitude, in electing a new Supreme Pontiff. With regard to myself, I wish to also devotedly serve the Holy Church of God in the future through a life dedicated to prayer."
The decision is almost unprecedented in the history of the Catholic Church.
The last pope to step down was Gregory XII, who led the Christian world between 1406 and 1415.
'Resignation a natural process'
Israel's Chief Rabbi Yona Metzger
praised Pope Benedict's inter-religious outreach and said relations between Israel and the Vatican had never been better.
"During his period (as pope) there were the best relations ever between the church and the Chief Rabbinate and we hope that this trend will continue," he said.
"I think he deserves a lot of credit for advancing inter-religious links the world over between Judaism,
Christianity and Islam."
'A human decision' (Photo: AFP)
French President Francois Hollande
commented on Benedict XVI's announcement saying it was "eminently respectable… This is a human decision and a decision related to a desire to be respected," he said.
The German government also issued a statement following the announcement, saying that the Bundestag
was "moved and touched" by the surprise resignation of German-born pope.
"As a Christian and as a Catholic, one can't help but be moved and touched by this," government spokesman Steffen Seibert
said at a regular government news conference.
"The German government has the highest respect for the Holy Father, for what he has done, for his contributions over the course of his life to the Catholic Church.
"He has been at the head of the Catholic Church for nearly eight years. He has left a very personal signature as a thinker at the head of the Church, and also as a shepherd. Whatever the reasons for this decision, they must be respected," Seibert added.
New merchandizing opportunity? (Photo: Reuters)
The pope's brother, Georg Ratzinger, said the Pontiff had been advised by his doctor not to take any more transatlantic trips and had been considering stepping down for months.
Speaking from his home in Regensburg,
Georg Ratzinger said his brother was having increasing difficulty walking and that his resignation was part of a "natural process."
"His age is weighing on him," the 89-year-old said of his 85-year-old brother. "At this age my brother wants more rest."
Archbishop of Canterbury Justin Welby, the spiritual head of the world's Anglicans said it was with a "heavy heart" that he learned of Pope Benedict's decision.
"It was with a heavy heart but complete understanding that we learned this morning of Pope Benedict's declaration of his decision to lay down the burden of ministry as Bishop of Rome, an office which he has held with great dignity, insight and courage," said the leader of the global 80-million-strong Anglican Communion.
"We pray that God will bless him profoundly in retirement with health and peace of mind and heart, and we entrust to the Holy Spirit those who have a responsibility to elect his successor," Welby said in a statement.
Reuters, Sharon Gilad, Liat Shpigler and AP contributed to this report