Peanut Corp of America says plant was inspected

The building of the now-closed Peanut Corporation of America plant is pictured in Blakely, Georgia on January 29, 2009. The company, which is at the center of a salmonella outbreak, said on Wednesday federal and state regulators regularly visited the plant in Georgia that has been identified as the source of the contamination.

CHICAGO (Reuters) - The U.S. peanut company at the center of a salmonella outbreak said on Wednesday federal and state regulators regularly visited a plant in Georgia that has been identified as the source of the contamination.

At least 550 people, more than half of them children, have been sickened in the United States and Canada. The infection may have contributed to eight deaths, health officials say.

The U.S. Food and Drug Administration has launched a criminal probe of Peanut Corp of America, which the agency said knowingly shipped "adulterated" products from a plant in the town of Blakely in Georgia.

The outbreak has forced one of the biggest food recalls in U.S. history and President Barack Obama has criticized the FDA's handling of food safety.

Several members of Congress have proposed an overhaul of the way the FDA works, with one bill being introduced on Wednesday that would separate its food regulatory duties from its oversight of pharmaceuticals and over-the-counter drugs.

"We want the public to know that there were regular visits and inspections of the Blakely facility by federal and state regulators in 2008," Peanut Corp of America said.

"Independent audit and food safety firms also conducted customary unannounced inspections of the Blakely facility in 2008," it said in a statement, noting the plant got an overall superior rating on one visit and, in another, was found to "meet or exceed" audit expectations.

The outbreak of the Salmonella Typhimurium strain has affected people in 43 states and one person in Canada, the U.S. Centers for Disease Control and Prevention says.

Last week, Peanut Corp of America expanded the recall to all products shipped from the plant since January 1, 2007, from the original date of July 1, 2008.

Hundreds of products have been pulled off shelves, including many store brands that used peanut products as ingredients. Major peanut butter brands in retail stores have not been affected.

(Editing by Maggie Fox and John O'Callaghan)