A US consumer group is demanding more disclosure on fastfood menu items, after the Hardee's chain launched its Monster Thickburger.

The burger has two one-third-pound patties laden with bacon and cheese, totalling 107 grams of fat and over 1,400 calories. The US Center for Science in the Public Interest called it "the fastfood equivalent of a snuff film".

The CSPI wants the Department of Health and Human Services to mandate tighter nutritional disclosure rules on promotional boards and company materials. A multi-million dollar ad campaign focuses on the burger's size. Hardee's says, "Given the way we've named and described this burger, it seems we've provided fair warning to the public."

The chain will unveil a barbecued chicken sandwich on a whole-wheat bun early next year.