The discovery of unmarked Indigenous graves on the eve of the 1 July Canada Day holiday has prompted calls for national celebrations to be cancelled.

The remains of 182 people near the grounds of a former residential school in British Columbia were found by the Lower Kootenay Band on Wednesday.

The discovery adds to a rising tally of unmarked grave sites across Canada.

Indigenous leaders have said they expect more graves will be found as investigations continue.

This most recent discovery fell on the eve of Canada Day, the nation’s founding holiday meant to mark the date in 1867 when three British colonies were joined to create the Dominion of Canada.

Many Indigenous people in Canada have never recognised Canada Day, a sentiment that has grown in recent weeks as more grave sites were found.

Municipalities across Canada have cancelled celebrations and statues of figures involved with residential schools have been vandalised or removed throughout the country.

“You can never fully prepare for something like this,” said Chief Jason Louie of the Lower Kootenay Band, which is a member of the Ktunaxa Nation.

The community of ʔaq’am, one of four bands in the Ktunaxa Nation, used ground-penetrating technology to uncover the gravesites close to the former St Eugene’s Mission School near Cranbrook, British Columbia.

The Indigenous nation said it is too early to say if the remains belonged to former students of the school.

Some remains were found in shallow graves, only 3-4ft deep, the Lower Kootenay Band said in a statement.

St Eugene’s was operated by the Catholic Church from 1912 until the early 1970s. It was one of more than 130 compulsory boarding schools funded by the Canadian government and run by religious authorities during the 19th and 20th Centuries with the aim of forcibly assimilating indigenous youth.

Up to 100 of the Lower Kootenay Band were forced to attend, the group said.

But the remains were found on the grounds of the ʔaq̓am cemetery, which dates back to 1865. Burial plots used to be marked with wooden crosses that crumbled over the years.

“These factors, among others, make it extremely difficult to establish whether or not these unmarked graves contain the remains of children who attended the St Eugene Residential School,” the community’s statement said.