Pope Francis will make his first public appearance on Sunday with a blessing and a wave from a window at Rome's Gemelli Hospital where he was admitted on February 14.

The 88-year-old pontiff has been battling pneumonia in both lungs after being hospitalised for breathing difficulties.

"Pope Francis intends to wave and offer a blessing from the Agostino Gemelli hospital in Rome after Angelus prayers," The Vatican said on Saturday.

The pope has stopped using an oxygen mask. After an earlier series of breathing attacks, his breathing has improved and the Vatican said on Monday he was spending short moments breathing on his own.

For most of the pope's hospital stay, including critical stages, the Vatican was publishing daily bulletins on the health of Francis, who had part of one lung removed as a young man.

The pope's illness and the long spell in hospital have raised questions over who might lead the busy schedule of religious events leading up to Easter, the holiest period in the Christian calendar. (AFP)