US food safety officials have written warning letters to 16 manufacturers that claim the companies have broken labelling laws.

Two Nestle divisions, snack group Diamond Foods and pie maker Schwan's Consumer Brands are among those to have received the letters in the last ten days, according to the FDA website.

The FDA letters issue a series of warnings to the companies on the health claims made on product labels and on brand websites.

Nestle divisions Dreyer's Grand Ice Cream and Gerber Products Co. are among the companies accused of misleading labelling.

In one example, the FDA said Gerber had made "unauthorised" claims over the nutritional content of its Gerber Graduates Fruit Puffs line on the product's labels. The foods make claims that they are "Healthy as Fresh," an "Excellent Source ... of Vitamin A" and "No Added Sugar," according to the agency letter. "These regulations do not allow the claim for products specifically intended for children under two years of age," the FDA wrote

The FDA ordered Gerber to take "complete corrective action" with 15 days to avoid further action, a timetable issued to a number of the companies.

Consumer watchdog the Center for Science in the Public Interest labelled the FDA's effort a "crackdown" on "deceptive labelling practices".