The discovery last month of the remains of the children at the Kamloops Indian Residential School in British Columbia, which closed in 1978, has reopened old wounds and is fuelling outrage in Canada about the lack of information and accountability.
The UN called on the Vatican to help investigate a mass grave found at a Catholic school for Indigenous children in Canada.
The Canadian government has admitted that physical and sexual abuse was rampant in the schools, with students beaten for speaking their native languages.
"I follow with pain the news coming from Canada about the shocking discovery of the remains of 215 children", he said, following Sunday prayers in Saint Peter's Square.
Pope Francis met today with two Canadian Cardinals as pressure mounts for the Catholic Church to take action and accept responsibility for the residential school system that targeted Indigenous children for decades. "The sad discovery further raises awareness of the pains and sufferings of the past".
Trudeau urged Canadian Catholics to "reach out (to their) local parishes, to bishops and cardinals, and make it clear that we expect the Church to step up and take responsibility for its role in this and be there to help in the grieving and the healing, including with records".
Trudeau has not directed such pointed comments at the Catholic Church over the residential schools since taking office in 2015. "It's something we are all still waiting for the Catholic Church to do", he said. The Missionary Oblates of Mary Immaculate, which ran almost half of Canada's residential schools, has yet to release any records about the Kamloops school, she also said.
Francis, who was elected pope in 2013, has already apologized for the Church's role in colonialism in the Americas but he has mostly chosen to make such apologies while visiting countries.
"May the political and religious authorities continue to collaborate with determination to shed light on this sad affair and to commit to a path of healing", Francis added.
People watch as a convoy of truckers and other vehicles travel in front of the former Kamloops Indian Residential School in support of the Tk'emlups te Secwepemc people after the remains of 215 children were discovered buried near the facility, in Kamloops, Canada, on June 5, 2021.
The United, Presbyterian and Anglican churches have apologized for their roles in the abuse, as has the Canadian government, which has offered compensation.