From the 19th century until the 1970s, more than 150,000 Indigenous children were forced to attend state-funded Christian schools, most run by Roman Catholic missionary congregations, in a campaign to assimilate them into Canadian society

Prime Minister Justin Trudeau said on Friday he has urged Pope Francis to come to Canada to apologise for church-run boarding schools where hundreds of unmarked graves have been found, and he said Canadians are “horrified and ashamed” by their government’s longtime policy of forcing Indigenous children to attend such schools.

Indigenous leaders said this week that 600 or more remains were discovered at the Marieval Indian Residential School, which operated from 1899 to 1997 in the province of Saskatchewan. Last month, some 215 remains were reported at a similar school in British Columbia.

From the 19th century until the 1970s, more than 150,000 Indigenous children were forced to attend state-funded Christian schools, most run by Roman Catholic missionary congregations, in a campaign to assimilate them into Canadian society.

Indigenous leaders have called for Pope Francis to apologise — a demand echoed again Friday by Mr. Trudeau, who said the pope should visit Canada to do it.