Pope Francis passed a quiet night in hospital, the Vatican said Sunday, after revealing that the 88-year-old was responding well to treatment for pneumonia.

"The night was calm, the pope is resting", the Vatican said in its brief morning update on the Argentine, who has been in a special papal suite at Rome's Gemelli hospital since 14 February.

The head of the Catholic Church has suffered several respiratory crises since his admission, but has not had any for several days now, with the Vatican describing his condition as "stable."

It said Saturday that Francis was responding well to treatment and had seen "a gradual, slight improvement."

Though Francis does not have a fever, his doctors want to see the same positive results "in the coming days" before giving a prognosis, an evening medical bulletin said.

Francis has suffered a series of health woes in recent years, from colon surgery in 2021 to a hernia operation in 2023, but this is the longest and most serious hospitalization of his papacy.

The leader of the world's 1.4 billion Catholics has in previous stays at the Gemelli appeared on a balcony for his weekly Sunday Angelus prayer.

But he has skipped the last three and is set to miss his fourth this Sunday, with the Vatican press office saying Saturday that the Angelus would be delivered "in the same way" as in previous weeks, when it was published as a letter at noon.