An Iowa company on Wednesday broadened a nationwide recall of its eggs to 380 million after some of its facilities were linked to an outbreak of salmonella that has sickened hundreds of people across the country.

The outbreak, which federal officials said was the largest of its type related to eggs in years, began in May, just weeks before new government safety rules went into effect that were intended to greatly reduce the risk of salmonella in eggs.

The company behind the recall, Wright County Egg, of Galt, Iowa, is owned by Jack DeCoster, who has had run-ins with regulators over poor or unsafe working conditions, environmental violations, the harassment of workers and the hiring of illegal immigrants.

The salmonella outbreak began in May, when several states began seeing an increase in the number of cases of a common type of bacterial illness known as Salmonella Enteritidis, said Dr. Christopher R. Braden, acting director of food-borne diseases at the Centers for Disease Control and Prevention in Atlanta. The numbers continued to grow, and in June and July, a database used to track disease nationwide found that the number of cases had risen from a historical average of about 50 a week to about 200.

Public health officials in California, Minnesota and Colorado determined that many of the people who had gotten sick had eaten food containing eggs. Further investigation traced many tainted eggs to Wright County Egg.

The company announced on Friday that it was recalling 228 million eggs that it had sold since mid-May. On Wednesday, it added another 152 million eggs to the recall. Many of the affected eggs have long since been cooked and eaten, but millions could still be stored in refrigerators.