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.

The frail 88-year-old Catholic leader suffered further setbacks in what has become a more than two-week battle to overcome a complex respiratory infection.

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.