VATICAN CITY (AP) — The health of Pope Emeritus Benedict XVI has worsened due to his age, and doctors are constantly monitoring the 95-year-old’s condition, the Vatican said Wednesday.

Vatican spokesperson Matteo Bruni said Pope Francis, who asked the faithful earlier Wednesday to pray for Benedict, went to visit his predecessor in the monastery on Vatican grounds where the retired pontiff has lived since retiring in February 2013.

“Regarding the health conditions of the emeritus pope, for whom Pope Francis asked for prayers at the end of his general audience this morning, I can confirm that in the last hours, a worsening due to advanced age has happened,” Bruni said in a written statement.

“The situation at the moment remains under control, constantly monitored by doctors,” according to the statement.

At the end of his customary Wednesday audience with the public in a Vatican auditorium, Francis departed from his prepared remarks to say that Benedict is “very sick” and asked the faithful to pray for the retired pontiff.

Francis didn’t elaborate on the condition of Benedict.

“I’d like to ask all of you for a special prayer for Emeritus Pope Benedict, who, in silence, is sustaining the church,″ Francis said in remarks near the end of an hour-long audience. ”I remind you that he is very sick,” Francis said.

“Let’s ask the Lord to comfort him and sustain him in this testimony of love to the church to the very end,″ Francis said.

After the hour-long audience, “Pope Francis went to the Mater Ecclesiae monastery to visit Benedict XVI. Let us all unite with him in prayer for the emeritus pope,″ Bruni said.

Benedict, who was the first pontiff to resign in 600 years, has become increasingly frail in recent years as he dedicated his post-papacy life to prayer and meditation.

When Benedict turned 95 in April, his longtime secretary, Archbishop Georg Gaenswein, said the retired pontiff was in good spirits, adding that, “Naturally he is physically relatively weak and fragile, but rather lucid.”

Francis called on Benedict at the monastery four months ago. The occasion was Francis’ latest ceremony elevating churchmen to cardinal rank, and the new “princes of the church” accompanied him for the brief greeting.

The Vatican released a photo at the time that showed a very thin-looking Benedict clasping a hand of Francis as they current and past pontiff smiled at each other.

In his first years of retirement, Benedict attended a couple of cardinal-elevating ceremonies in St. Peter’s Basilica. But in recent years, he wasn’t strong enough to attend the long service.