During a meeting of Vatican cardinals this morning, the Pope said he could no longer continue in the role because of his age and diminishing strength.
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. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only by 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 St Peter and proclaim the Gospel, both strength of mind and body are necessary - strengths which in the last few months, has deteriorated in me to the extent that I have had to recognise my incapacity to adequately fulfil the ministry entrusted to me.
Pope Benedict XVI announced his resignation on February 11, 2013, the first Pontiff to do so since Pope Gregory XII in 1415.
The Pope's brother Georg Ratzinger said he had known of the resignation plans "for months", according to German magazine Der Spiegel.
Ratzinger added that his brother wanted "more quiet" in his old age and his decision was part of a "natural process."
His age is weighing on him. At this age my brother wants more rest.
Tributes have been paid to Pope Benedict by political and religious leaders across the world, with David Cameron praising his work on strengthening Britain's "relations with the Holy See."
I send my best wishes to Pope Benedict following his announcement today. He has worked tirelessly to strengthen Britain's relations with the Holy See. http://www.itv.com/news/update/2013-02-11/pictures-of-pope-benedicts-2010-visit-to-britain/ is remembered with great respect and affection. He will be missed as a spiritual leader to millions.