Washington, D.C. ? Federal agents searched facilities of a dog and cat food manufacturer and one of its suppliers as part of an investigation into the widening recall of pet products, the companies disclosed Friday.

Food and Drug Administration officials searched an Emporia, Kan., pet food plant operated by Menu Foods and the Las Vegas offices of ChemNutra Inc., according to the companies.

Menu Foods made many of the more than 100 brands of pet food recalled since March 16 because of contamination by the chemical melamine. ChemNutra supplied the manufacturer with wheat gluten, one of the two ingredients tainted by melamine used in recalled pet products. Both companies said they were cooperating with the investigation.

Menu Foods also said the U.S. Attorney’s offices in Kansas and the western district of Missouri have targeted the company as part of misdemeanor investigations into whether it violated the federal Food, Drug and Cosmetic Act. The sale of adulterated food is a misdemeanor.