Deadly microbes were found in government labs from historical collections that were long-forgotten, but the National Institutes of Health said they have now been destroyed.

BBC reported that a number of NIH labs had found highly poisonous substances after an accidental discovery of vials of smallpox, believed to be dead, and located in six freeze-dried and sealed vials, in July.

Vials of ricin and pathogens that cause botulism, the plague and a rare tropical infection were found, some almost 100 years old, BBC reported.

"NIH takes this matter very seriously. The finding of these agents highlights the need for constant vigilance in monitoring laboratory materials in compliance with federal regulations on biosafety,'' said a memo from the agency, BBC reported.

NIH officials said some of its labs were cleared to use poisonous substances, and checked regularly, but some of the collections found were from a time when they were allowed to be stored without regulation.

Although they were stored improperly, they were in sealed containers, so there was no risk to employees.

The discovery in July spurred an unprecedented sweep of government labs, according to the Washington Post.

As a result, the Food and Drug Administration said it had found vials of staphylococcal enterotoxin, a frequent cause of food-borne illness, at a lab not registered to handle it.

"These things were stored in locations where they should not have been stored," Alfred Johnson, director of the NIH's office of research services, told the Washington Post. "All of these were found in containers that were intact, and there have been no exposures. It reminds us, just like my garage at home, that from time to time, we need to check."

A sweep that lasted about one month, from July 29 to Aug. 27, produced the improperly stored collections.

"The finding of these agents and toxins highlights the need for constant vigilance in monitoring laboratory materials in compliance with federal regulations on biosafety," NIH Director Francis Collins wrote in an e-mail to employees, the Washington Post reported.