Pope Francis knelt at the tomb of St Peter and donned the symbols of papal power at a sumptuous inauguration on Tuesday, vowing to embrace the “poorest, the weakest” of humanity.

Nearly 200,000 pilgrims cheered Latin America’s first pontiff in St Peter’s Square, waving flags from around the world as the newly elected popes promised that his would be a “lowly, concrete and faithful” papacy.In an address strongly influenced by the teachings of St Francis of Assisi, the saint he has chosen as his inspiration, he urged world economic and political leaders not to “allow omens of destruction and death to accompany the advance of this world!”

His voice raised in emotion, the 76-year-old Francis said a pope must “embrace with tender affection the whole of humanity, especially the poorest, the weakest, the least important.”“Amid so much darkness, we need to see the light of hope,” said the Argentinean, after touring a sun-drenched St Peter’s Square in an open-top car to cries of “Long live the pope!”

The former Buenos Aires Cardinal Jorge Bergoglio was a fervent critic of the International Monetary Fund and unregulated market capitalism – a stance that could make him an important voice in an austerity-hit Europe.At the ceremony, the 265th successor to St Peter received from his cardinals the papal pallium – a lambs wool strip of cloth that symbolises the pope’s role as a shepherd and has red crosses to represent the wounds of Jesus Christ.

The “Fisherman’s Ring” bestowed on him by Angelo Sodano, dean of the college of cardinals, is a personalised signet ring traditionally worn by popes in honour of St Peter – a fisherman.“With Pope Francis, the Church will be closer to the people and to the modern world,” said Rodrigo Grajales, a 31-year-old Colombian priest.Francis gave the thumbs-up as he toured the square, stopping to kiss babies and getting out of the car at one point to bless a disabled man.

“Go Francis! We Will Be With You Wherever You Go!” read a sign held up by a group of Brazilian nuns in St Peter’s Square.Sister Rosa, an elderly Italian nun, said she expected the pope would be “another St Francis on Earth for love, goodness, poverty and humility”.The Vatican said there were between 150,000 and 200,000 people present at the ceremony.The son of an Italian immigrant railway worker, Francis has already won hearts in Rome with a disarmingly informal style which contrasted with Tuesday’s pomp and ceremony.

Vatican experts say he has also signalled he will pursue a more inclusive “collegial” style of leadership together with the cardinals and bishops.Vast crowds also gathered on the other side of the Atlantic outside the Buenos Aires cathedral to dance and sing as they watched the inauguration.Catholic high school students chanted slogans praising Francis, while seminarians and nuns waved Vatican flags and signs supporting the new pope.

“This pope has awakened deep emotions within me, not only because he’s from Argentina, but because of his warmth as a person,” Celia Farias, 33, told AFP.“As a Catholic, it has renewed my faith.”