Pope Francis urges world: Pray for sick Benedict - Holy Father 'very ill' at Vatican

Pope Francis has asked the faithful to pray for the retired Pope Benedict XVI after his condition suddenly “worsened due to age” in recent hours.

His predecessor did not share exact details on Benedict’s condition during the surprise appeal at the end of his general audience.

The 95-year-old became the first pope to resign in 600 years due to his “deteriorating health” in 2013.

Following his resignation, Benedict has been living in the Vatican.

Pope Francis said: "I'd like to ask all of you for a special prayer for Emeritus Pope Benedict, who, in silence, is sustaining the church. I remind you that he is very sick.

"Let's ask the Lord to comfort him and sustain him in this testimony of love to the church to the very end."

After the service ended, Pope Francis went to visit Benedict.

A Vatican spokesperson confirmed that he is receiving constant medical care and his condition is “under control”.

In recent years, Benedict has become increasingly frail after dedicating his post-papacy life to prayer and meditation.

Some senior members of the clergy and canon lawyers - those with significant knowledge about the legal system within the Catholic Church – have questioned Benedict’s decisions on retirement.

Some dispute his decision to continue wearing the white cassock of the papacy and his refusal to revert to his birth name Joseph Ratzinger.

In his resignation letter he said: "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."

Pope Francis asked for prayers for Benedict just days after he called for an end to the “senseless” war in Ukraine.