A "very large" avalanche in western Canada has left at least five people on snowmobiles dead, authorities say.

The avalanche struck near the community of McBride, north-east of Vancouver in the province of British Columbia.

A spokesman for the Avalanche Canada monitoring service said the "very large, significant" avalanche was triggered by human activity.

Reports from British Columbia say the avalanche struck three separate groups of snowmobilers.

They were helped by a search and rescue team that happened to be in the area at the time, The Province newspaper reported.

Karl Klaasen, of Avalanche Canada, said there was a high risk of more incidents in the region, after heavy snow and rainfall over the past few days.