Scientists said Tuesday that six glass vials found in a storeroom in a government laboratory outside Washington contained the smallpox virus. It was the second incident in a month that revealed government mishandling of potentially deadly infectious agents.

The sealed vials were discovered on July 1 in a Food and Drug Administration lab at the National Institutes of Health in Bethesda, Md. The vials, which were labeled “variola,” another name for smallpox, were sent on Monday to the Centers for Disease Control and Prevention in Atlanta, where tests showed that they contained smallpox, the C.D.C. said in a statement. Additional tests to determine whether the smallpox is viable will take about two weeks, the centers said, after which the samples will be destroyed.

Biosafety personnel “have not identified any infectious exposure risk to lab workers or the public,” the C.D.C. said.

Smallpox was declared eradicated in 1980 following a long worldwide public health campaign. Until now, the only known samples of the virus were at high-security labs at the C.D.C. in Atlanta and in Russia.