Former Pope Benedict XVI has died at his Vatican residence at the age of 95.
In a statement, the Vatican said he died at the Mater Ecclesiae monastery at 9.34am on Saturday.
The statement added: “With sorrow I inform you that the Pope Emeritus, Benedict XVI, passed away today at 9:34 in the Mater Ecclesiae Monastery in the Vatican.
“Further information will be provided as soon as possible.”
The former head of the Catholic Church stood down in 2013, becoming the first to do so since 1415.
Benedict, who was born Joseph Ratzinger in Germany, was elected Pope in 2005 at the age of 78, becoming one of the oldest to hold the position.
Previously, Pope Francis called for prayers to be given to Benedict during his final audience of the year.
King Charles also expressed his “deep sadness” at Benedict's death in a message to his successor Pope Francis.
In a statement, Charles paid tribute to Benedict and recalled visiting him at the Vatican in 2009.
He said: "Your Holiness, I received the news of the death of your predecessor, Pope Emeritus Benedict XVI, with deep sadness.
"I remember with fondness my meeting with His Holiness during my visit to the Vatican in 2009. His visit to the United Kingdom in 2010 was important in strengthening the relations between the Holy See and the United Kingdom.
"I also recall his constant efforts to promote peace and goodwill to all people, and to strengthen the relationship between the global Anglican Communion and the Roman Catholic Church."
Cardinal Vincent Nichols, the head of the Roman Catholic Church in England and Wales, said Benedict was "one of the great theologians of the 20th century".
In a statement, he said: "I am deeply saddened to learn of the death of Pope Benedict. He will be remembered as one of the great theologians of the 20th century.
"I remember with particular affection the remarkable Papal Visit to these lands in 2010. We saw his courtesy, his gentleness, the perceptiveness of his mind and the openness of his welcome to everybody that he met.
"He was through and through a gentleman, through and through a scholar, through and through a pastor, through and through a man of God - close to the Lord and always his humble servant.
"Pope Benedict is very much in my heart and in my prayers. I give thanks to God for his ministry and leadership."