A century-old sword used by a founder of Manitoba has gone missing and is believed stolen from a festival celebrating Métis heritage.

Louis Riel's Toledo steel sword was taken on Saturday from a pavilion at Saskatchewan's Back To Batoche festival.

The festival is celebrating 125 years of Métis culture and history.

Henry Hall, who collects, preserves and tours Canada with Riel's artifacts, said the priceless sword was on display before it vanished. It was one of many Riel artifacts Hall had on display at the festival.

Hall, who spoke to CBC News about the incident while vacationing in Petersfield, Man., said he left the sword in trustworthy hands.

"The artifacts were in good hands, in people's hands that I trust thoroughly," said Hall. "I guess evidently the pavilion was really, really full. [The sword was] out so people could look at it [and] see Riel is not a myth."

Hall said the historic weapon is about three feet long, has a brass handle and the initials L.R. stamped into it.

"It's priceless," Hall said. He added that although there are probably other Toledo steel swords like it, what gives this one its value is "the fact that it was stamped with Riel's initials and that it was Riel's sword."

Hall said the RCMP have been called in to investigate.

Riel was an MP and leader of the Métis people, and is considered a founder of the province of Manitoba.

He was hanged for treason in 1885 at the age of 41 after leading Métis resistance in Saskatchewan against the Canadian government.

Batoche is about 90 kilometres north east of Saskatoon.