Wal-Mart Stores Inc. in the United States are recalling a house brand of trail mix after three customers in two states reported finding glass or hard plastic inside, the company said Tuesday.

Maryland-based Ann's House of Nuts, which manufactures the product, has started an investigation at its production plant. The company has sent bags of the trail mix to a lab for analysis.

No injuries have been reported.

Jim Giles, the vice president of quality assurance for Ann's, said investigators have not found any signs of deliberate tampering.

The recall involves Sam's Choice "Nature Trail" with a best before date of April 23, 2007. The product also bears a manufacturing date of Oct. 23, 2006.