Pope Francis' doctors on Monday lited a "guarded prognosis" though he will need to remain in the "hospital setting for a period of time" in the treatment of double pneumonia, the Vatican said.

The 88-year-old pope has remained stable, with no fever and good oxygen levels in his blood for several days, doctors said.

Pope Francis is no longer in immediate danger of death and is responding well to treatment in hospital, the Vatican said on Monday, in a sign of progress as the 88-year-old pontiff battles double pneumonia.