Pope Francis on Sunday expressed sorrow over the discovery in Canada of the remains of 215 Indigenous students of church-run boarding schools but didn't offer the apology sought by the Canadian prime minister.

Francis, in remarks to faithful gathered in St. Peter's Square, called on political and church authorities to work to shed light on what he called "this sad affair" and to foster healing.

Two days earlier, Prime Minister Justin Trudeau said he was deeply disappointed that the Vatican hadn't offered an apology, and called on the church to take responsibility. From the 19th century until the 1970s, more than 150,000 Indigenous children were forced to attend state-funded Christian schools, the majority of them run by Catholic missionary congregations, in a campaign to assimilate them into Canadian society.

Ground-penetrating radar was used to confirm the remains of the children at the Kamloops Indian Residential School in Kamloops, British Columbia, last month. The school was Canada's largest such facility and was operated by the Catholic church between 1890 and 1969.

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 sorrow the news that arrives from Canada about the upsetting discovery of the remains of 215 children," Francis said in his customary Sunday noon remarks to the public.

"I join with the Catholic church in Canada in expressing closeness to the Canadian people traumatized by the shocking news," Francis said. "This sad discovery increases the awareness of the sorrows and sufferings of the past."

"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.

Trudeau on Friday blasted the Church for being "silent" and "not stepping up," and called on it to formally apologize and to make amends for its prominent role in his nation's former system of church-run Indigenous boarding schools. He noted that when he met with Francis at the Vatican in 2017 he had asked him to "move forward on apologizing" and on making records available. But, Trudeau said,"`we're still seeing resistance from the church, possibly from the church in Canada."

Francis' comments spoke of healing but not of apology. "These difficult moments represent a strong call to distance ourselves from the colonizing model and from today's ideological colonizing and to walk side by side in dialogue, in respect and in recognizing cultural rights and values," he said. (AP)