A suspect batch of anthrax has reportedly been sent to three laboratories in Canada, expanding the number of countries that have received live samples of the deadly bacteria from a US Army laboratory in Utah.
According to the Public Health Agency of Canada, the country received the sample in August 2006, but it had not been used for more than five years.
Countries, including South Korea and Australia, have also received the specimens of the deadly Bacillus anthracis.
The shipment was reportedly sent from a batch that was meant to have been inactivated at the Dugway Proving Ground in Utah.
The US Centers for Disease Control and Prevention said that the number of laboratories that have received live anthrax has risen to at least 28 labs in 12 states and the District of Columbia.
In an email written to state officials CDC Office of Public Health Preparedness and Response deputy director Daniel Sosin wrote: "We have concern that the inactivation procedures, when followed properly, are inadequate to kill all spores, and the US government is developing an approach to securing such possible samples from misuse."
One of the shipments was intended for the Pentagon's police force, who uses the samples to detect chemical and biological agents.
The US Department of Defense (DoD) has launched a comprehensive review of its laboratory procedures, processes, and protocols associated with inactivating spore-forming disease, Anthrax.
The DoD has asked laboratories to stop working with those samples until further instruction from the US department and CDC.
After the CDC investigation is complete, the Pentagon will conduct its own investigation with respect to any apparent lapses in performance, and ensure appropriate accountability.