Former pope Benedict, 95, who in 2013 became the first pontiff in 600 years to step down, is “very sick”, his successor Pope Francis said on Wednesday, asking the church to pray for him.

The Vatican later said Benedict had suffered a sudden“worsening” of his health in recent hours. It also said his condition was “under control”.

“I would like to ask all of you for a special prayer for Pope Emeritus Benedict, who, in silence, is sustaining the Church,” Francis said. “Letus remember him. He is very sick, asking the Lord to console and sustain him in this witness of love for the Church, until the end.”

Francis, who visited the former pontiff shortly after his general audience, has often praisedBenedict, saying it was like having a grandfather in a home. But the presence of two men dressed in white in the Vatican has at times been troublesome.

Conservatives have looked to the former pope as their standard bearer and some ultra-traditionalists even refused to acknowledge Francis as a legitimate pontiff.

One of the latest known photographs of Benedict was taken on December 1, when he met the winners of a prize for theologians named after him. He was seated and looked exceptionally weak.