Pope Francis thanked those who prayed for him during his illness Sunday, as he kicked off the holiest week in the Christian calendar just a day after leaving the hospital following a bout of bronchitis.

The 86-year-old's admittance to hospital in Rome on Wednesday with breathing difficulties sparked concerns he may not be well enough to attend an important series of Easter rites.

But Francis had promised to be present, and he waved briefly to some 60,000 people as he rode in his popemobile through the square, which was adorned with more than 35,000 plants and flowers.