The government disclosed new details Friday about the discovery of contaminated peanuts sent abroad by the same plant linked to a national salmonella outbreak, acknowledging a shipment containing a "filthy, putrid or decomposed substance" was returned to the U.S. in April — months earlier than reflected in a federal tracking database.

The rejected shipment — coming across a bridge between New York and Canada — was logged by the Food and Drug Administration but never tested by federal inspectors, according to government records. The incident took place in mid-September, the records show, weeks before the earliest signs of the outbreak.

The FDA said Friday the shipment of chopped peanuts from Peanut Corp. of America in Blakely, Ga., was returned to the U.S. in April 2008. The peanuts eventually were destroyed, after back-and-forth efforts between the FDA and Peanut Corp. broke down and after the FDA rejected as "unacceptable" findings by a private lab hired by Peanut Corp. to analyze the company's peanuts.

"The shipment was refused by FDA for filth," FDA spokeswoman Stephanie Kwisnek wrote in an e-mail to The Associated Press. "The importer requested to destroy the product."

"The FDA did everything appropriately in handling the activities associated with this shipment," Kwisnek said.

The FDA's explanation Friday raises new questions about the adequacy of food-safety tests arranged by Peanut Corp. of its own products. The FDA said it refused to accept the private lab analysis because of problems with the size of the sample tested, lack of information about whether experienced and trained workers conducted the test, and questions about whether the test could have detected certain types of metals.