Fires on Saturday destroyed two more Catholic churches in indigenous communities in western Canada, following grim discoveries at former church-run indigenous residential schools of nearly 1,000 unmarked graves.

St. Ann's Catholic Church on the Upper Similkameen Indian Band and the Chopaka Catholic Church on the Lower Similkameen Indian Band were set ablaze less than an hour apart in the early morning, federal police said.

"Both churches have been destroyed," Sergeant Jason Bayda of the Royal Canadian Mounted Police said in a statement.

Authorities consider the two fires "suspicious, and are looking to determine any possible connection to the church fires in both Penticton and Oliver on June 21, 2021," he said.

The Penticton and Oliver fires -- about 50 kilometers (30 miles) away -- are still under investigation.

The destruction of the four churches comes at a raw time for many of Canada's indigenous peoples still struggling with the discovery, using ground-penetrating radar mapping, of the remains of 215 schoolchildren at a former residential school in Kamloops last month, and 751 more unmarked graves at another school in Marieval this week.

On Friday, Prime Minister Justin Trudeau apologized for the "harmful" government policy of indigenous assimilation applied at 139 of these schools across Canada until the 1990s, and called on Pope Francis to do the same.

Some 150,000 indigenous, Inuit and Metis youngsters were taken from their communities and forcibly enrolled at the residential schools.

Many were subjected to ill-treatment and sexual abuse, and more than 4,000 died of disease and neglect in the schools, according to a truth and reconciliation commission that concluded Canada had committed "cultural genocide."