The Center for Science in the Public Interest, a non-profit consumer advocacy group, filed a class action lawsuit against General Mills Monday, alleging the cereal manufacturer is misleading customers about one of its latest products, Cheerios Protein. In the federal class action suit, filed in the Northern District of California, CSPI cites its side-by-side comparison of Original Cheerios and Cheerios Protein as evidence that General Mills is marketing Cheerios Protein as a "high protein, healthful alternative to Cheerios" when it does not contain much more protein than Original Cheerios. "Rather than protein, the principal ingredient that distinguishes Cheerios Protein from Cheerios is sugar," the suit says. The Nutrition Facts Panel on the boxes cite a 4 gram difference in protein (7 for Cheerios Protein as opposed to 3 for the original) -- a "smidgen" -- but the suit attributes that to a larger serving size (55 grams as opposed to 27 respectively). For the same 200 calories, CSPI found a mere .7 gram difference between Cheerios Protein Oats and Honey (6.7 grams) and Original Cheerios (6 grams), the suit says. The court documents also contend that Cheerios Protein has significantly more sugar than Original Cheerios. A 1 1/4-cup serving of Cheerios Protein Oats and Honey has 17 grams as opposed to 1 gram for a 1 cup serving of original Cheerios, the suit says. A 1 1/4 –cup serving of the Cinnamon Almond variety has 16 grams, according to the documents. Advertising for Cheerios Protein says it's a "great start to your day" along with pictures of "appealing photographic images depicting healthy and successful kids and parents," the claim says. "These claims and images are part of a sophisticated marketing campaign to encourage parents to purchase Cheerios Protein for their children; and the sweet taste of the product helps ensure that children will eat the product," the suit says. “People are being cheated. Not only is General Mills giving you so much more sugar, they’re also charging you more for this product,” said CSPI Executive Director Michael Jacobson, in an interview with ABC News’ Jim Avila. ABC News also found Cheerios Protein Oats and Honey also has more sugar than every other variety of Cheerios on the market with 10.2 grams for a 3/4 cup serving. Apple Cinnamon Cheerios has the second most with 10 grams and third is Cheerios Protein Cinnamon Almond at 9.6 grams. Frosted Cheerios, Fruity Cheerios and Chocolate Cheerios have 9 grams each, the calculations found. In a statement to ABC News, General Mills said, “An equal amount of Cheerios Protein contains 18 percent more protein by weight than original Cheerios. Original Cheerios does contain 3 grams of protein per serving – and it’s clearly a great cereal choice. But it doesn’t meet the FDA requirement as a good source of protein. Cheerios Protein contains 7 grams of protein per serving – and it does qualify as a good source of high-quality protein under the FDA standard. Cheerios Protein is accurately labeled – and provides a good source of protein in every labeled serving.” They did not, however, respond to repeated questions about the amount of sugar it contains.