New Delhi, July 3 -- The U.S. Food and Drug Administration (FDA) has issued its most serious warning for contaminated organic blueberries. Alma Pak International recalled 400 boxes (12,000 pounds) of berries after routine tests found Listeria monocytogenes, a deadly bacteria.

The Georgia-based company shipped the tainted fruit to one customer in North Carolina before catching the problem in June.

By July 1, the FDA declared this a "Class I recall" - meaning eating these berries could cause severe sickness or death. The risky blueberries carry lot numbers 13325 G1060 and 13325 G1096. Though the company claims no berries reached grocery stores, the FDA warns everyone to check their freezers and avoid these products completely.Listeria isn...