VATICAN CITY (REUTERS) - Pope Francis said on Sunday (June 6) that he was pained by the discovery of the remains of 215 children at a former Catholic school for indigenous students in Canada and called for respect for the rights and cultures of native peoples.

However, Francis stopped short of the direct apology some Canadians had demanded. Two days ago, Canadian Prime Minister Justin Trudeau said the Catholic Church must take responsibility for its role in running many of the schools.

Indigenous leaders and school survivors said the Church needed to do much more.

"We're all pained and saddened. Who isn't?" said Bobby Cameron, chief of the Federation of Sovereign Indigenous Nations in Saskatchewan.

Speaking to pilgrims and tourists in St. Peter's Square for his weekly blessing, Francis urged Canadian political and Catholic religious leaders to "cooperate with determination" to shed light on the finding and to seek reconciliation and healing.

Francis said he felt close to "the Canadian people, who have been traumatised by the shocking news".

The residential schools operated between 1831 and 1996 and were run by a number of Christian denominations on behalf of the government. Most were run by the Catholic Church.

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 a lack of information and accountability.

"The sad discovery further increases the understanding of the pain and suffering of the past," Francis said.

"These difficult moments represent a strong reminder for all of us to distance ourselves from the model of coloniser ... and to walk side by side in dialogue and in mutual respect in the recognition of the rights and cultural values of all the sons and daughters of Canada," he said.

The residential school system forcibly separated about 150,000 children from their homes. Many were subjected to abuse, rape and malnutrition in what the Truth and Reconciliation Commission in 2015 called "cultural genocide".

"Let us commend to the Lord the souls of all of the dead children in the residential schools of Canada and let us pray for the families and the native communities of Canada shattered by pain," he said, before asking the crowd to join him in silent prayer.

Francis, who was elected pope 17 years after the last schools was closed, has already apologised for the Church's role in colonialism in the Americas.

But he has mostly chosen to make direct apologies while visiting countries and talking to native peoples. No papal visit to Canada is scheduled.

Visiting Bolivia in 2015, Francis apologised for the "many grave sins (that) were committed against the native people of America in the name of God".