A pair of marijuana growers in western Canada appear to have been using bears to protect their illegal crop, but the well-fed animals proved to be a bit lax in their guard duties, police say.

Police say officers were dismantling two large outdoor plots of marijuana near Christina Lake, British Columbia, when they realised there were 10 large black bears wandering around the farm property.

Officers were initially worried the bears might be dangerous but soon realised the animals were very docile and content to sit around as the marijuana was seized.

Two people were arrested in connection with the drugs.

The bears, which were apparently being fed dog food to keep them on the property, may eventually have to be put down if wildlife officials determine they have become to habituated to humans.

- Reuters