Federal regulators asked the Coca-Cola Company to change the label on a version of its Diet Coke brand containing vitamins and minerals, saying that the soft-drink maker makes incorrect nutritional claims.

The Diet Coke Plus soft drink contains zinc, magnesium and vitamin B, but these amounts are unquestionably insufficient to claim that the product is a source of vitamins and minerals, according to the Food and Drug Administration. Foods labeled "plus" ought to have at least 10 percent more nutrients than comparable items, the agency wrote in a letter to the beverage company, issued on Dec. 10 and posted on the FDA website 15 days later.

"Your Diet Coke Plus product is mislabeled... .because the product makes a nutrient content claim but does not meet the criteria to make that claim," federal health regulators wrote in the letter. 

The “misbranded” item was released in the UK in October 2007, available in two variants, one with vitamins B3, B12, and vitamin C, and the other one containing antioxidants with extra green tea and vitamin C.

The FDA gave the world’s largest soft-drink maker 15 days to tell how it plans to fix the violation of the Federal Food, Drug and Cosmetic Act, a set of laws passed in 1938 which lays down the conditions in which a company is allowed to make nutritional and health claims.