The announcement doubled the number of incidents in the US. A smaller number of shipments were revealed last week.
Staff members at some of the labs have been treated for anthrax exposure as a precaution, but no-one has fallen ill.
The Pentagon has maintained there is no risk to the general public.
The Centers for Disease Control and Prevention (CDC) is leading the investigation into the incidents.
According to defense official Robert Work, the number of affected laboratories is expected to rise.
Experts in biosafety have heavily criticized the lapse and called for improved precautions.
Symptoms of anthrax exposure include skin ulcers, nausea, vomiting and fever, and can cause death if untreated.
The military has ordered all of its labs that have previously received inactive anthrax samples to test them. In addition it is advising all labs to cease working with these samples until told otherwise.
Pentagon officials say there was no sign the live samples were sent due to any deliberate action.
The samples were mailed from a Utah army facility by commercial post to laboratories over the past 10 years.
In addition to the US labs, samples were sent to facilities in Australia, Canada and South Korea.
Three Indian nationals have been arrested and charged over the killing of Sikh separatist leader…
President Joe Biden has urged pro-Palestinian protesters on university campuses to uphold the rule of…
Blue Ivy Carter has joined the voice cast of The Lion King prequel Mufasa: The…
At least five people, including a four-month-old baby, have been killed after dozens of tornadoes…
Harvey Weinstein has been hospitalized just days after his 2020 rape conviction in New York…
Hamas has published a video showing the first proof of life of US and Israeli…