Pope Francis, who has been hospitalised for over a week, remains in "critical" condition after developing an "asthmatic respiratory crisis" earlier on Saturday, CNN quoted the Vatican as saying in a statement.

The death of a sitting pope initiates a profound period of mourning and transition within the Roman Catholic Church, marked by a meticulously structured process to elect a new pontiff

The Vatican said Francis, who was diagnosed with double pneumonia, suffered a breathing crisis and needed blood transfusions.