Pope Francis declared on Sunday that his visit to Canada the next week will be a “pilgrimage of penance” meant to atone for the wrongs that abusive Roman Catholic priests and nuns who administered residential schools had done to native people.

Francis will fulfill a pledge to apologize to native people on their home territory for the Church’s involvement in state-approved institutions that tried to eradicate indigenous customs by having at least five encounters with them during the trip from July 24 to 30.

“Unfortunately in Canada many Christians, including some members of religious orders, contributed to the policies of cultural assimilation that in the past gravely damaged native populations in various ways,” Francis said at his weekly address to people in St. Peter’s Square.

About 150,000 children were taken from their homes. Many were subjected to abuse, rape and malnutrition in what Canada’s Truth and Reconciliation Commission in 2015 called “cultural genocide”.

The stated aim of the schools, which operated between 1831 and 1996, was to assimilate indigenous children. They were run by Christian denominations on behalf of the government, most by the Catholic Church.

The schools were at the centre of discussions between the pope and indigenous people at the Vatican in March and April. Recalling the meetings, Francis said on Sunday he had expressed “my pain and solidarity over the evil that they endured”.

“I am about to make a pilgrimage of penance, which, I hope that with the grace of God can contribute to the path of healing and reconciliation that already has been started,” he said.

The 85-year-old pope will visit Edmonton, Maskwacis, Lac Ste. Anne, Quebec, and Iqaluit in Canada’s Arctic territory. He is scheduled to deliver nine homilies and addresses and say two Masses.

The recurring schools scandal broke out again last year with the discovery of the remains of 215 children at the former Indian Residential School in Kamloops in the Western Canadian province of British Columbia. The school closed in 1978.

The discovery brought fresh demands for accountability. Hundreds more unmarked burial sites have been found since.

Francis was elected pope nearly two decades after the last schools closed.

The pope had to cancel a trip to Democratic Republic of Congo and South Sudan in early July because of a knee problem that forced him to use first a wheel chair and later a cane.

In an interview with Reuters on July 2, he gave details of his ailment for the first time public, saying he had suffered “a small fracture” in the knee when he took a misstep while a ligament was inflamed.