On Friday, Pentagon said Japan is among the list of countries that received live anthrax samples mistakenly from the US military.

According to Defense Department spokesman Colonel Steve Warren, the samples were sent to the US military base of Camp Zama about 25 miles (40 km) southwest of Tokyo in 2005.

The US military sent active anthrax bacteria samples to 69 laboratories since 2005 in 19 states including the he US capital Washington and five countries, which include South Korea, Canada, Australia and Britain.

Last week, senior defense officials admitted that the problem of mistaken shipments was worse than initially reported. They also said that the extent of the problem remained unclear.

Till now, nobody has fallen sick from handling the samples, and the concentration of active bacteria is extremely low. Officials have also insisted that there is no threat to public health.

Pentagon officials said that investigators are trying to gauge whether the accidental shipments of the anthrax stemmed from quality control problems at a US base in Utah, the Dugway Proving Ground.

The military is testing more than 400 lots of supposedly dead anthrax it keeps at four military facilities. Some 11 of 91 lots have tested positive for anthrax, and all of those are from the Dugway facility.

CDC spokesman Jason McDonald said, "If the labs are able, destroy the samples in accordance with standard procedures and with an approved method. The destruction must be completed within 7 days and evidence of the destruction provided to CDC".