Mother Teresa of Calcutta has been proclaimed a saint by Pope Francis in a ceremony at the Vatican on Sunday.

“We declare and define Blessed Teresa of Calcutta to be a saint and we enroll her among the saints, decreeing that she is to be venerated as such by the whole Church,” the Pope said.

In his homily of St Teresa’s work, Pope Francis said “she had shone a light in the darkness of the many who no longer had tears to shed for their poverty and suffering.”

Pope Francis said St Teresa had spent her life “bowing down before those who were spent, left to die on the side of the road, seeing in them their God-given dignity.”

“She made her voice heard before the powers of the world, so that they might recognise their guilt for the crimes of poverty they themselves created,” he said.

Tens of thousands of pilgrims attended the canonization in St Peter’s Square.

Two apparent cures of sick people after Mother Teresa’s death in 1997 have been attributed to her intercession.

In India, a special Mass was celebrated at the Missionaries of Charity, the order she founded in Calcutta.

Despite the intense heat, the atmosphere among the pilgrims in St Peter’s Square was one of joy, and the service a celebration of the life of this extraordinary woman.

Although critics have sought to portray St Teresa as a sinner and a hypocrite, her supporters have been just as vocal in her defence, challenging those critics to live their lives the way St Teresa did, before they cast the first stone.

Hundreds of Missionaries of Charity sisters attended the event, along with 13 heads of state or government.

Some 1,500 homeless people across Italy were also brought to Rome in buses to be given seats of honour at the celebration – and then a pizza lunch served by 250 nuns and priests of the Sisters of Charity order.

Born in 1910 to ethnic Albanian parents, Agnese Bojaxhiu grew up in what is now the Macedonian capital, Skopje, but was then part of the Ottoman Empire.

Aged 19, she joined the Irish order of Loreto and in 1929 was sent to India, where she taught at a school in Darjeeling under the name of Therese.

In 1946, she moved to Kolkata to help the destitute and, after a decade, set up a hospice and a home for abandoned children.

She founded the Missionaries of Charity in 1950. The sisterhood now has 4,500 nuns worldwide.

Mother Teresa was awarded the Nobel Peace Prize in 1979 “for work undertaken in the struggle to overcome poverty and distress, which also constitutes a threat to peace.”