WASHINGTON (AP) ― The same U.S. government scientist who recently found forgotten samples of smallpox at a federal lab also uncovered over 300 additional vials, many bearing the names of highly contagious viruses and bacteria. The new revelations raise serious concerns about the government’s ability to secure its collections of potentially deadly pathogens.

Food and Drug Administration officials said Wednesday the undocumented collection contained 327 carefully packaged vials, listing pathogens like dengue, influenza and rickettsia. Last week the government only disclosed that it had recovered six glass vials of smallpox dating from the 1950s.

“The reasons why these samples went unnoticed for this long is something we’re actively trying to understand,” said FDA deputy director for biologics Dr. Peter Marks.

The samples, including those labeled smallpox, were found in 12 boxes in a corner of a cold storage room at the National Institutes of Health in suburban Washington that has been used by the Food and Drug Administration since 1972. FDA officials estimate the collection was assembled between 1946 and 1964 by government scientists.

“The fact that these materials were not discovered until now is unacceptable,” said Karen Midthun, of FDA’s director for biologics. “However, upon finding these materials our staff did the right thing ― they immediately notified the appropriate authorities who secured the materials and determined there was no exposure.”

FDA scientists said they have not yet confirmed whether the newly disclosed vials actually contained the pathogens listed on their labels. The agency is conducting a nationwide search of all cold storage units for any other missing samples.

Investigators destroyed 32 vials containing tissue samples and a non-contagious virus related to smallpox. Several unlabeled vials were sent to the Centers for Disease Control and Prevention for testing and the remaining 279 samples were shipped to the Department of Homeland Security for safekeeping. FDA officials said there is no evidence anyone was exposed to any of the agents, which were packed in heat-sealed glass vials with no signs of leakage.

The finding of freeze-dried smallpox samples was disturbing because smallpox was declared eradicated in 1980, and world health authorities said the only known samples left were safely stored in super-secure laboratories in Atlanta and in Russia.

It was the second recent incident in which a U.S. government health agency appeared to have mishandled a highly dangerous biologic agent. Last month, scores of employees at the CDC in Atlanta were feared exposed to anthrax because of a laboratory safety lapse. The CDC began giving them antibiotics as a precaution.

In separate congressional testimony Wednesday, CDC director Dr. Tom Frieden acknowledged that systemic safety problems have for years plagued federal public health laboratories that handle dangerous germs such as anthrax and bird flu. Frieden added that his agency had long thought of the lapses as unrelated accidents.