(Reuters) - Kraft Foods Group Inc said on Tuesday it was recalling about 242,000 cases of Kraft Macaroni & Cheese dinners, due to the risk that they may contain small pieces of metal.

The recall comes at a time when Kraft’s Macaroni & Cheese products, a staple for generations of American children, face increasing competition from smaller brands with more natural ingredients.

And, it follows a similar recall less than four years ago.

In September 2011, the company recalled about 137,000 cases of Velveeta Shells & Cheese single-serve cups due to the possible presence of small, thin wire bristle pieces.

Kraft said the latest recall applied to 7.25-ounce packs of “original” flavor of the product with “best when used by” dates of Sept. 18, 2015 through Oct. 11, 2015 with the manufacturing code “C2”.

“We believe a piece of stainless steel got wedged in a metal piece of equipment, which may have generated friction that resulted in small pieces of metal potentially falling into the product,” Joyce Hodel, a Kraft spokeswoman, said in a statement.

“We deeply apologize to the consumers we have disappointed.”

Some of the recalled products were also sold in three-, four- and five-pack boxes, Kraft said on Tuesday.

No injuries had been reported and the company had received eight consumer contacts about the issue.

Northfield, Illinois-based Kraft said the affected boxes were shipped across the United States, Puerto Rico, and some Caribbean and South American countries.

Kraft said the affected product should not be consumed and should be returned to the store where purchased for an exchange or full refund.

In August, Kraft recalled about 7,700 cases of some varieties of its Kraft American Singles after a supplier failed to store an ingredient correctly.

Kraft’s shares closed at $61.70 on Tuesday on Nasdaq.

(This story has been refiled to correct the day in first paragraph)