Pope Francis, who has been diagnosed with pneumonia in both lungs, passed a "peaceful night," the Vatican said Wednesday, amid growing concerns over the 88-year-old's condition.

"The pope spent a peaceful night, woke up, and had breakfast," the Vatican said after Francis's fifth night at the Gemelli hospital in Rome.

Francis was admitted with bronchitis last week after suffering breathing difficulties, but has since developed pneumonia in both of his lungs.

Though the Argentine pontiff was in "good spirits," the Vatican warned late Tuesday that "the laboratory tests, chest X-ray, and the Holy Father's clinical condition continue to present a complex picture."

It said Tuesday that a "polymicrobial infection" which has come on top of "bronchiectasis and asthmatic bronchitis, and which required the use of cortisone antibiotic therapy, makes therapeutic treatment more complex.

"The follow-up chest CT scan which the Holy Father underwent this afternoon... demonstrated the onset of bilateral pneumonia, which required additional drug therapy," it said.

The pontiff had part of his right lung cut away when he was 21, after developing pleurisy that almost killed him.

The Vatican has already canceled a papal audience on Saturday and said he would not attend a mass on Sunday, although it has yet to announce plans for his weekly Angelus prayer, held on Sunday.

Francis, the head of the Catholic Church since 2013, was admitted to hospital after struggling for several days to read his texts in public.

It is the latest of a series of health issues for the Jesuit, who has undergone hernia and colon surgery since 2021 and uses a wheelchair due to pain in his knee.

The Jesuit has left open the option of resigning if he became unable to carry out his duties.

But in a memoir last year he said it was just a "distant possibility" that would be justified only in the event of "a serious physical impediment."