The image released by US Department of Defense shows Bacillus anthrax vegetative cells and spores. (AFP)
The Pentagon said on Wednesday that 51 labs in 17 U.S. states and three foreign countries have received suspected live samples of anthrax - a larger number than previously disclosed - and that the number may rise as an investigation continues.
The Defense Department said there is no sign that the sending of the samples of the potentially lethal bacteria was the result of deliberate action. The Pentagon said there were no signs of anyone becoming infected or any danger to the public.
The Pentagon previously disclosed the three foreign countries as Australia, South Korea and Canada.
The Pentagon said the only confirmed live anthrax samples came from a U.S. Army base in Utah, the Dugway Proving Ground.
The Pentagon had said on Tuesday that suspect anthrax samples had been sent to labs in 12 U.S. states as well as those three countries as far back as 2006. The Pentagon last week ordered a sweeping review of practices meant to inactivate the bacteria.
The Pentagon's handling of anthrax further raised concerns about the U.S. government's stewardship of such dangerous pathogens. This follows last year's disclosure that the U.S. Centers for Disease Control and Prevention similarly mishandled anthrax.
© Thomson Reuters 2015