The Pentagon has revealed a UK laboratory accidentally received live anthrax samples from the US military.

The British lab and another in Massachusetts have been added to a list of laboratories that were mistakenly sent the shipments of anthrax, which can be used as a biological weapon.

The samples were sent in 2007 to a company, which destroyed them shortly after testing, the UK's Health and Safety Executive said in a statement.

It added: "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."

The deadly spores are supposed to be made harmless before being shipped out for research.

Investigators are trying to determine whether the problem stemmed from quality control issues at a US Army base in Utah where the samples came from, defence department officials said.

Some 66 labs in 19 US states, Australia, Canada and South Korea are already known to have received the samples.

Last week it was found that the US sent more live samples than previously thought.

The military was accused of a "serious breach of trust" in its obligations to protect civilians.

But the Pentagon said there is "no known risk" to the general public and an "extremely low risk" to lab workers.

The lethal disease is spread by spores and has been used for bioweapons programmes in the US and elsewhere.

Its microscopic spores can be released without being detected and can be placed in powders or food.

The disease is deadly unless a patient is quickly given large doses of antibiotics.