Updated 11.30am

Pope Francis has appealed for prayers for his predecessor Pope Benedict XVI who, he said, is "very ill".

The 95-year-old, who now lives quietly in Vatican City, became the first pope to resign in 600 years when he stepped down in 2013. 

At the end of his general audience on Wednesday, Francis said he was praying for Benedict. 

"I would like to ask all of you to pray a special prayer for Pope Emeritus Benedict," Francis said.

He called on people to "remember him, because he is very ill, asking the Lord to console and support him".

The Vatican confirmed Benedict's health has worsened "in the last few hours" and said Francis visited him after his audience.

"In the last few hours there has been a deterioration due to advancing age," spokesman Matteo Bruni said in a statement.

"The situation at the moment remains under control, monitored continually by doctors."

Back in 2013, he had cited his declining physical and mental health in his decision to become the first pope since 1415 to give up the job as head of the worldwide Catholic church.

The German pope emeritus, whose real name is Joseph Ratzinger, has been living a quiet life in a former convent inside the Vatican.

His resignation created an unprecedented situation in which two popes - Benedict and his successor, Pope Francis - have co-existed within the walls of the tiny city state.

In April, Benedict's long-time secretary, Archbishop Georg Gaenswein, told Vatican News the ex-pope was "physically relatively weak and fragile", but "in good spirits".

God's Rottweiler

Benedict was 78 when he succeeded the long-reigning and popular John Paul II in April 2005.

His papacy was beset by Church infighting and outcry over paedophilia.

He became the first pontiff to apologise for the scandals that emerged around the world, expressing "deep remorse" and meeting with victims in person.

But while he took key steps to tackling clerical child abuse, he was criticised for failing to end Church cover-ups.

The abuse scandal has returned to haunt him in retirement.

A damning report for the German church in January 2022 accused him of personally failing to stop four predatory priests in the 1980s while archbishop of Munich.

Benedict has denied wrongdoing and the Vatican has strongly defended his record.

Unlike his successor Pope Francis, a Jesuit who delights in being among his flock, Benedict is considered a conservative intellectual.

He was dubbed "God's Rottweiler" in a previous post as chief doctrinal enforcer.

But as pontiff he appeared overwhelmed by the challenges facing a Church that was losing influence and followers, and years of Vatican turmoil took their toll.

He stepped down in February 2013 in an announcement delivered to cardinals in Latin, later saying that the decision was the result of a mystical experience.

Pope Francis (right) and Pope Emeritus Benedict XVI meeting with new cardinals last August. File photo: AFP, Vatican media