Pope Francis was in stable condition Tuesday and breathing with just the help of supplemental oxygen after respiratory crises a day earlier, but will resume using a ventilation mask at night, the Vatican said.

The Vatican on Tuesday called the health condition of Pope Francis "guarded" and "complex" as he remained in a stable condition with double pneumonia, according to officials.

Pope Francis, who suffered two respiratory crises on Monday as he battles double pneumonia, has stabilised and no longer needs to use mechanical ventilation for help breathing, the Vatican said on Tuesday.