U.S. health regulators issued a warning letter to Staples Inc, the largest U.S. office supply retailer, for violating certain manufacturing practices related to food products stored in a company facility in California.

The U.S. Food and Drug Administration alleged, in a letter dated March 7, that the products have been prepared, packed, or held under insanitary conditions and may have become contaminated with filth, or injurious to health.

The agency said that rodent waste was found in close vicinity of packages of different food products, including candies, crackers, creamers, pistachios, ramen noodles, and bottled water.

FDA inspected Staples' Stockton, California-based facility during October 20 to November 3, 2011. (Reuters)