Updated

Pope Benedict XVI called on world leaders to unite in the fight against poverty Sunday and sent two doves flying into St. Peter's Square in a symbol of peace, continuing a tradition begun by his predecessor, John Paul II.

From his studio window overlooking the square, Benedict offered a special greeting to those who suffer from leprosy, a disfiguring condition also known as Hansen's disease that affects hundreds of thousands of people worldwide.

Noting that Sunday was World Day of Leprosy sufferers, the pontiff encouraged missionaries, health care personnel and volunteers working in the field against the scourge.

"Leprosy is a symptom of a more serious and vaster ill, which is poverty," Benedict told pilgrims, tourists and a group of Italian Catholic children in the square.

"For this reason, following in the wake of my predecessors, I renew the appeal to leaders of nations so that they will unite their efforts to overcome the grave imbalances that still penalize a large part of humanity."

Cardinal Javier Lozano Barragan, the Vatican's top official for health issues, urged international organizations and governments on Saturday to develop more efficient networks to distribute free medicine and improve hygiene in fighting leprosy.

Benedict, together with two children at his window, released a pair of doves into the square and laughed when one of the white birds darted back inside his studio.

"The dove wants to stay with the pope but it will find its freedom," Benedict said, and one of the children gave the bird another push to fly.

The birds did not go very far, perching on a cornice just below the window on the Apostolic Palace.

Benedict told the children in the square that by always saying the truth "you will become builders of peace."

The release of the doves in January became a tradition under John Paul. A Jan. 30, 2005, appearance at the window by John Paul with the children and doves was one of his last in public.

On that occasion, he chuckled and watched with delight as he shooed a dove out the window into the cold air, but the bird flew back inside. John Paul grabbed the bird and tried to set it free, but it again fluttered back inside.

Later that day, the 84-year-old pontiff, who suffered from Parkinson's disease, came down with the flu. A few days later he was hospitalized, the first of two hospitalizations before his death in April.