A U.S. Food and Drug Administration spokeswoman has said that Hillandale Farms and Wright County Egg, following a salmonella outbreak, recalled half a billion eggs and federal agents visited these farms.

Patricia El-Hinnawy said that the agents were at two Iowa locations.

Further questions were referred by her to the U.S. attorney's office in Cedar Rapids, Iowa.

Hillandale Farms spokeswoman Julie DeYoung said that New Hampton office was visited by the FDA investigators. She further said that she can not state the exact time for which the officials were there or any material was taken by them.

A Wright County Egg facility in Galt was also visited by the agents.

Wright County Egg spokeswoman Hinda Mitchell said, "I can only confirm that, yes, there were FDA officials at the farm, and that we continue to fully cooperate with their review of the farm, as we have been doing throughout this process."

It was also stated by FDA Commissioner that an investigation that is beyond farm inspections will be joined by the criminal division of the FDA and the Justice Department.