WASHINGTON (Reuters) - The Pentagon on Tuesday added Britain to the list of countries that received live anthrax samples from the U.S. military.

The samples were sent to a company in Britain in 2007, a spokesman for Britain's Health and Safety Executive said. The agency declined to name the company.

Besides the lab in Britain, another in Massachusetts was added to the list of laboratories that received live anthrax samples, said Army Colonel Steve Warren, a Defense Department spokesman, raising the total number of labs to 68.

"The company has informed us it destroyed samples shortly after testing," the British Health and Safety spokesman said in a statement. "On this basis we do not believe there is any continuing health risk to staff or to the public.

"We look forward to speaking with the US Department of Defense to understand how this issue arose in 2007 and how they will ensure similar situations are avoided in the future."

Four countries outside the United States are now known to have received live anthrax samples: Australia, Canada, South Korea and Britain. Labs in 19 states and Washington, D.C., also received live samples.

Investigators are trying to determine whether the inadvertent shipments of the anthrax, which can be used as a biological weapon, stemmed from quality control problems at the U.S. base, the Dugway Proving Ground, Pentagon officials said.

(Reporting by David Alexander, additional reporting by Kylie MacLellan in London; Editing by Doina Chiacu, Larry King)