Pope Francis called for "a poor Church for the poor" as he addressed thousands of the world's press on Saturday, saying he chose his papal name because St Francis of Assisi shunned riches to help the destitute.
But the former Jorge Mario Bergoglio, the first pope from Latin America, faced fresh accusations that he had failed to speak out about the brutalities committed by Argentina's military leaders during the "Dirty War".
The special audience with journalists in a Vatican auditorium was billed as another sign of the greater openness that has characterised the new pope's first days in office.
In between bursts of applause from the audience, the 76-year-old said his papal name was inspired by St Francis of Assisi, who was "a man of poverty and a man of peace".
"How I would like a poor Church for the poor!" he said.
Francis described the emotional moments immediately after his election in a conclave in the Sistine Chapel on Wednesday, offering a rare insight from a pope into deliberations which are supposed to remain secret.
He explained that when the cardinals elected him, he had been sitting next to Brazilian Cardinal Claudio Hummes, the archbishop emeritus of Sao Paulo.
"He hugged me and kissed me and told me not to forget the poor. And that word went in here," Francis said, pointing to his head.
"I immediately thought of Francis of Assisi," he said.
"Francis of Assisi for me is a man of poverty, a man of peace, a man who loved and protected Creation. Right now our relations with Creation are not going very well," he added.
Showing the informal style that is already characterising his reign, Francis departed from the script to tell the journalists with a smile: "You've worked, hey? You've worked!"
He was presented to members of the media and Vatican staff, including one woman who gave him a cup and straw to drink mate, the South American tea he is known to enjoy.
The Vatican said Francis would meet his predecessor Benedict XVI next Saturday at the papal summer residence Castel Gandolfo outside Rome where the now "pope emeritus" has been staying since his historic resignation last month.
Benedict, 85, became the first pope to resign for 700 years when he abruptly ended his eight-year reign saying his health was no longer robust enough for the job.
The two men know each other well and Bergoglio is believed to have been runner-up to the German in the 2005 election, but the Argentinian's open style contrasts sharply with that of his more academic predecessor.
Speaking in a folksy Italian, he has urged Catholic leaders to shun worldly glories and lead a spiritual renewal in the Church that will reach "the ends of the earth", or risk becoming little more than a charity with no spiritual foundation.
The Catholic Church has been rocked in recent years by multiple scandals including thousands of cases of abuse of children by paedophile priests, stretching back decades, and intrigue in the Vatican bureaucracy.
Catholics are also abandoning churches in huge numbers in an increasingly secularised West.
A moderate conservative in Argentina where he was the archbishop of Buenos Aires, Francis -- the son of an Italian emigrant railway worker -- is unlikely to change any of the fundamental tenets of Catholic doctrine but he could push for more social justice and a friendlier faith.
Experts have said his priorities will also include reforming the administration of the Church and the Vatican bank, which is being investigated for money laundering.
The Vatican on Friday rejected claims that Francis had failed to protect two Jesuit priests who were kidnapped and tortured by Argentina's brutal military junta during the 1976-1983 "Dirty War", during which 30,000 died or disappeared.
But the Grandmothers of the Plaza de Mayo organisation, founded in 1977 to help locate children kidnapped during the years of military rule, added to the criticism of the new pope when it accused him of failing to speak out against the former military rulers.
"He has never spoken of the problem of people who had disappeared under dictatorial rule, and 30 years have already passed since our return to democracy," said Estela Carlotto, the head of the group, whose daughter Laura was abducted and killed during the military era.
Francis's inauguration mass will take place on Tuesday -- the Feast of St Joseph, the patron saint of the universal church.
He has urged the faithful in Argentina not to travel to Italy for the mass but rather to donate the money for the trip to charity. Nonetheless, more than a million people are expected to throng Rome and heads of state from all over the world will attend.
Francis's surprise election is seen as recognition of the Church's power in Latin America, which is home to 40 percent of the world's Catholics.