Canadian brewer Labatt has launched an ad campaign that attacks rival Molson Coors and its flagship brand Coors Light.

Labatt, the Canadian arm of brewing giant InBev, has launched a website condemning claims from Molson Coors that Coors Light is brewed in the Rocky Mountains.

The site, www.rockymountaintruth.com, says that the Coors Light sold in Ontario - a key Canadian beer market - is brewed in the province and not in the Rockies.

Labatt labels Coors Light the "not-so-real mountain beer" and contrasts it with its own Kokanee brand, which is brewed in Creston, British Columbia.

Coors Light is sold in Canada as brewed according to a "Rocky Mountain recipe" but, Labatt claims, is made in a number of various Molson Coors breweries. The Coors Light sold in the US, however, is brewed in the Rockies.

Labatt officials failed to return requests for comment as just-drinks went to press. Molson Canada officials could also not be reached for comment.