VATICAN CITY - Pope Francis, who was admitted to hospital last week, has developed pneumonia in both of his lungs, the Vatican said, adding that the 88-year-old was in "good spirits".
"The laboratory tests, chest X-ray, and the Holy Father's clinical condition continue to present a complex picture", the Vatican said in a statement.
Francis was admitted to Rome's Gemelli hospital last Friday for bronchitis, but the Vatican on Monday said it was changing his treatment following tests.
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 had already cancelled 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.
"Nevertheless, Pope Francis is in good spirits," it added.
The pope spent his fifth day in hospital alternating rest with prayer and reading texts, the Vatican said.