Police have seized weapons, ammunition and survival gear from what they say is a remote mountain training camp for a right-wing American militia group.
No arrests have been made, and police said the people suspected of assembling the arms cache are in the United States.
"We know who these people are and who they are connected to," said Sgt. Peter Montague, a Royal Canadian Mounted Police spokesman. "We are working with U.S. authorities and can't identify the group at this time other than to say it is a right-wing militia group."
The weapons included automatic rifles and a .50-caliber machine gun -- all prohibited in Canada.
The raid on the camp took place almost three months ago, but was not disclosed until Thursday. Police said the arms were concealed in the floor of a trailer.
The camp was near Smithers, a town of about 5,000 in rugged countryside about 420 miles northwest of Vancouver.