Mother Teresa has been made a saint of the Roman Catholic Church, 19 years after her death.
The ceremony to proclaim the Nobel peace prize laureate, who is recognised globally for her work with poor people in the slums of Kolkata in India, drew 100,000 pilgrims from around the world to St Peter's Square in Vatican City.
"For the honour of the Blessed Trinity … we declare and define Blessed Teresa of Kolkata to be a saint and we enrol her among the saints, decreeing that she is to be venerated as such by the whole Church," Pope Francis, who presided over the ceremony, said in Latin.
Photo: Pope Francis led the mass of 100,000 people. (AFP: Andreas Solaro) The pontiff said that even though the nun had been declared a saint, she would always be Mother Teresa to the Catholic family.
Echoing his own vision of a "poor church for the poor", Pope Francis described Mother Teresa's work as "eloquent witness to God's closeness to the poorest of the poor".
"Mother Teresa loved to say, 'perhaps I don't speak their language but I can smile'," he said.
"Let us carry her smile in our hearts and give it to those whom we meet along our journey, especially those who suffer." Pope Francis also used his sermon to recall Mother Teresa's fervent opposition to abortion, which she termed "murder by the mother" in a controversial Nobel Peace prize speech in 1979.
Millions of Catholics revere her as a model of compassion, and the Vatican could easily have issued double the number of tickets but for space and security restrictions.
Helicopters had earlier buzzed over the headquarters of the Roman Catholic Church, testifying to the huge but relatively discreet security operation under way. Around 3,000 officers were on duty to ensure the day passed off peacefully. Among the assembled crowd were 1,500 poor people looked after by the Italian branches of Teresa's order, the Missionaries of Charity. After the mass they attended a giant pizza lunch at the Vatican as Francis's guests, served by 250 sisters and 50 male members of the order. St Peter's Basilica was bathed in sunlight for the occasion and decked out with a tapestry of the late nun in her trademark blue-hemmed white robes.