The Pope today gave Australia its first saint when he canonised Mary MacKillop, a nun who was briefly excommunicated.

Benedict XVI also declared five other saints in a mass attended by tens of thousands of people.

Speaking in Latin on the steps of St Peter's Basilica, the pontiff read out the names of the six new saints, declaring each one worthy of veneration in all the Catholic church.

Cheers broke out in the crowd when Mary MacKillop's name was announced – evidence of flag-waving Australians celebrating the 19th century nun who was briefly excommunicated, in part because her order exposed a paedophile priest.

An estimated 10,000 people gathered at the Sydney chapel where Mary MacKillop is buried and at the city's Catholic cathedral, where a wooden cross made from floorboards taken from the first school MacKillop established was placed on the steps.

Born in 1842, Mary MacKillop grew up in poverty as the first of eight children of Scottish immigrants. She moved to the farming town of Penola, in South Australia, to become a teacher, inviting the poor and Aborigines in the area to attend free classes in a six-room stable.

She co-founded her order, the Congregation of the Sisters of St Joseph of the Sacred Heart, with the aim of serving the poor, the sick and the disadvantaged, particularly through education.

"She supported Aboriginal people because she believed in supporting people who were disadvantaged," Melissa Brickell, a pilgrim from Melbourne who was in Rome for today's service, said.

"She is a friend of Aboriginal people from the early days."

Mary MacKillop was eligible for sainthood after the Vatican approved a second miracle attributed to her intercession – that of Kathleen Evans, who was cured of lung and brain cancer in 1993.