US federal food safety officials said a California plant was recalling about one million pounds (454 tonnes) of pistachio products following fears of salmonella contamination.
The Food and Drug Administration (FDA) said it was investigating pistachio products sold by Setton Pistachio of Terra Bella Inc, California, the second-largest pistachio processor in the United States.
The company has stopped all distribution of processed pistachios, the FDA added, noting its joint investigation with the California Department of Public Health (CDPH) was under way.
Setton said it had issued a voluntary recall Tuesday of specific lots of bulk roasted shelled pistachios and roasted in-shell nuts.
"Because the pistachios were used as ingredients in a variety of foods, it is likely this recall will impact many products," the FDA warned in a statement.
The contamination was linked to several strains of salmonella, which can cause serious and sometimes fatal infections in people with weak immune systems, such as children and the elderly, it added.
The FDA said it was not yet known whether any of the found salmonella strains were linked to an outbreak.
The food safety agency cautioned consumers to avoid eating pistachios until it had determined the scope of the contamination and said it was conducting genetic testing of pistachio samples.
Kraft Foods alerted the FDA on May 24 that it had detected salmonella contamination in pistachio nuts contained in its Back To Nature Trail Mix. The food company issued a recall of the product after identifying Setton as the source of the pistachio contamination.
A devastating salmonella outbreak traced to a peanut processing plant in the southern state of Georgia has left nine people dead and nearly 700 sick since late last year.
The culprit, Peanut Corp of America, processed peanuts in plants infested with rodents and animal excrement, prompting the recall of over 2,000 different products from grocery shelves.