ST. LOUIS — Nestle Purina PetCare Co. filed suit Tuesday against Blue Buffalo Co. Ltd., accusing it of misleading consumers about the ingredients in its dog and cat foods.

The lawsuit accuses Wilton, Connecticut-based Blue Buffalo of false advertising, disparagement and unjust enrichment. It was filed in U.S. District Court in St. Louis, where Purina is based.

The pet food industry has seen a trend toward premium foods, with consumers showing more willingness to spend more on food perceived to be better for their animals. Sales of more expensive brands rose 68 percent from 2002 to 2012, compared with 19 percent for midpriced brands and 8 percent for economy brands, according to Euromonitor International.

Nestle Purina has been part of the trend, reporting solid growth in its high-end “made with natural ingredients” Beyond line.

Blue Buffalo advertises that its pet foods contain natural ingredients and do not contain chicken or poultry byproduct meals. The company also says the pet foods do not contain corn, wheat or soy – potential allergenss.

The suit claims that testing by an independent lab and funded by Purina showed that several Blue Buffalo products contained “significant” percentages of poultry byproduct meal and corn. The suit also says several products promoted as “grain-free” contain rice hulls.