Dhaka, April 22 -- Pope Francis died of a stroke and irreversible heart failure, Vatican doctor Andrea Arcangeli said in a death certificate released on Monday for the 88-year-old pontiff.

The certificate, which was published by the Vatican, said the pope had fallen into a coma before his death early on Monday.

The pontiff's death ended an often turbulent reign in which he repeatedly clashed with traditionalists and championed the poor and marginalized, reports Reuters.

Francis, 88, spent five weeks in hospital earlier this year for double pneumonia. But he returned to his Vatican home almost a month ago and had seemed to be recovering, appearing in St Peter's Square on Easter Sunday.

His sudden death set in motion ancient rituals, as...