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By Jim Miklaszewski

The Pentagon on Friday said it has identified five more potentially live anthrax shipments inadvertently shipped to laboratories, and has instructed labs which received inactive samples to stop working with the materials until further notice.

A total of 24 laboratories in 11 states and two foreign countries — Australia and South Korea — are believed to have received suspect samples, the Department of Defense said in a statement.

Defense officials tell NBC News the anthrax spores had been irradiated to kill them in 2008.

Officials have been testing samples thought to have been inactivated ever since it turned out the Army's Dugway Proving Grounds in Utah sent potentially live spores to labs.

Related: What you Need to Know About the Anthrax Blunder

Deputy Secretary of Defense Bob Work on Friday ordered a comprehensive review of Defense Department laboratory procedures and protocols associated with inactivating spore-forming anthrax, the Defense Department said.

Experts say it's very difficult to inactivate a large batch of anthrax spores and say it's a problem across U.S. labs. The Centers for Disease Control and Prevention, which is helping investigate the matter, says no member of the public is in danger and people who may have been exposed to the anthrax spores are taking antibiotics just to be safe.