A Canadian researcher has found that nutritional labels detailing fat content on pre-packaged foods may not be accurate on many popular products.

University of Guelph food science professor Bruce Holub tested hundreds of products over eight years, ranging from baby biscuits and waffles to pancake mix and chicken fingers, and found many "have values on the label on the carton which are not correct values based on direct analysis."

Even allowing for Canadian rules permitting 20% variability on labels, up to 15% of products surveyed exceeded limits, with breaded fish sticks and frozen breakfast waffles the worst offenders.

Canada's Food Inspection Agency investigated 123 food label complaints last year, resulting in fines for six companies.