WASHINGTON -- A major manufacturer of store-brand acetaminophen recalled 11 million bottles of the pain-relieving pills Thursday after discovering some were contaminated with metal fragments.

There were no immediate reports of injuries or illness.

Perrigo Co. said it discovered the metal bits during quality-control checks. The company passed 70 million pills through a metal detector and discovered the metal in about 200 caplets, according to the Food and Drug Administration. The fragments ranged in size from "microdots" to portions of wire one-third of an inch long.

The recall affects bottles containing various amounts of 500-milligram caplets. Consumers can determine if they are in possession of a recalled product by locating the batch number printed on the container label. The full list of batches is on the FDA's Web site.

Perrigo bills itself as the world's largest manufacturer of store-brand nonprescription drugs. The Allegan, Mich., company did not disclose the chains for which it manufactures the store-brand acetaminophen. A list of batch numbers and store brands affected by the recall was forthcoming, the FDA said.

Wal-Mart, BJ's, Kroger and CVS are among the big chains that sold the painkiller.

Perrigo said the pills contained raw material purchased from a third-party supplier and affected 383 batches.

Acetaminophen is best known as the drug in products sold under the Tylenol brand but is widely available in generic versions. The recall does not affect Tylenol.

The voluntary recall is considered a Class II recall since it covers products that might cause a temporary health problem or pose only a slight threat of a serious nature, according to the FDA.

The FDA said that consumers who believe they are in possession of the affected products should discontinue use immediately and call Perrigo's Consumer Affairs Department at 877-546-0454 for further instructions. Any adverse reactions experienced with the use of this product should be reported to Perrigo at the above number and the FDA's MedWatch Program by phone at 800-FDA-1088, by fax at 800-FDA-0178 or on the MedWatch Web site at www.fda.gov/medwatch.

Consumers who swallow any of the contaminated pills could suffer minor stomach discomfort or possible cuts to the mouth and throat, the FDA said, adding that the risk of serious injury was remote. Anyone who suspects they have been injured should contact their doctor, the agency said.

The recall should not cause a shortage of acetaminophen, the FDA said. Currently, only one strength (500 mg caplets) is affected.

Consumers may wish to take additional amounts of the lower strengths of acetaminophen tablets or caplets, which are not affected by this recall, to reach the 500 mg dose or access acetaminophen produced by alternate manufacturers.

In all instances, the FDA advises consumers to follow labeled instructions for maximum daily dosage.

The FDA said Perrigo began investigating after realizing the equipment it uses to make pills was wearing down prematurely.