The US military says it accidentally sent live anthrax spores to as many as nine laboratories and is investigating how that happened.
There was no public threat from the mishap, a Pentagon official claimed on Wednesday.
The labs were supposed to receive dead anthrax samples for research use.
Pentagon spokesman Col. Steve Warren said the military was working with the Centers for Disease Control and Prevention to retrieve the samples.
According to the Pentagon, samples came from a military lab at Dugway Proving Ground (DPG), Utah, Army facility.