Pope Francis said that his predecessor, Benedict XVI, is very ill, and asked the crowds of worshipers in the Vatican to pray for him.
Pope Benedict, 95, is the first Pope of the Catholic Church to step down in 600 years, due to his advanced age, in 2013.
Pope Francis, at the end of the last meeting this year, asked people to offer a “special prayer to Pope Benedict”.
The Vatican added that the health of the former pope had deteriorated in the past hours.
Spokesman Matteo Bruni said: “The situation at the present time is still under control and is being monitored by doctors constantly.”
Pope Francis was addressing a general audience in Paul VI Hall in the Vatican, when he looked at a paper and spoke of the failing health of his predecessor.
He also went to visit him in the monastery of Mater Ecclesia (Mother of the Church), where Benedict had lived since his abdication.
Benedict was the first pope to renounce the papacy in nearly six hundred years.
Earlier this month, Pope Francis revealed that he had been visiting his predecessor frequently.
Pope Francis spoke of Benedict as a “saint” and a man of sublime spiritual life, who said he was pure and had a good sense of humour.
He told the Spanish newspaper ABC: “He speaks softly, but he follows your conversation.”
Pope Benedict XVI, whose real name is Joseph Ratzinger, was 85 years old when he surprised Catholics around the world in February 2013 with his decision to step down, less than eight years after his election.
He is the first pope to step down since Pope Gregory XII in 1415.
He mentioned in a statement that he was relinquishing his post, and he mentioned the deterioration of his physical and mental health. Since then, the German-born pope has lived a quiet life in the Mater Ecclesia monastery.
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