Pope Francis on Monday apologised for the Catholic Church’s cooperation with Canada’s “catastrophic” policy of indigenous residential schools, saying the forced assimilation of native peoples into Christian society destroyed their cultures, severed families and marginalised generations.

“I am deeply sorry,” Francis said to applause from school survivors and indigenous community members gathered at a former residential school south of Edmonton, Alberta.

The Roman Potiff frowned at what he called the school policy a “disastrous error” that was incompatible with the Gospel and said further investigation and healing is needed.

“I humbly beg forgiveness for the evil committed by so many Christians against the Indigenous peoples,” Francis said.

In the first event of his weeklong “penitential pilgrimage,” Francis traveled to the lands of four Cree nations to pray at a cemetery and then deliver the long-sought apology at nearby powwow ceremonial grounds.

Four chiefs escorted the pontiff in a wheelchair to the site near the former Ermineskin Indian Residential School, and presented him with a feathered headdress after he spoke, making him an honourary leader of the community.

Francis’ words went beyond his earlier apology for the “deplorable” abuses committed by missionaries and instead took institutional responsibility for the church’s cooperation with Canada’s “catastrophic” assimilation policy, which the country’s Truth and Reconciliation Commission said amounted to a “cultural genocide”.

More than 150,000 native children in Canada were forced to attend government-funded Christian schools from the 19th century until the 1970s in an effort to isolate them from the influence of their homes and culture.

The aim was to Christianise and assimilate them into mainstream society, which previous Canadian governments considered superior.

Ottawa has admitted that physical and sexual abuse was rampant at the schools, with students beaten for speaking their native languages.

That legacy of that abuse and isolation from family has been cited by indigenous leaders as a root cause of the epidemic rates of alcohol and drug addiction now on Canadian reservations.

The discoveries of hundreds of potential burial sites at former schools in the past year drew international attention to the schools in Canada and their counterparts in the United States.

The revelations prompted Francis to comply with the truth commission’s call for an apology on Canadian soil; Catholic religious orders operated 66 of the country’s 139 residential schools.

Reflecting the conflicting emotions of the day, some in the crowd wept as Francis spoke, while others applauded or stayed silent listening to his words, delivered in his native Spanish with English translations.

The first pope from the Americas was determined to make this trip, even though torn knee ligaments forced him to cancel a visit to Africa earlier this month.

The six-day visit — which also includes stops in Quebec City and Iqaluit, Nunavut, in the far north — follows meetings Francis held in the spring at the Vatican with First Nations, Metis and Inuit delegations.