The number of workers at U.S. Centers for Disease Control and Prevention who could have been exposed to anthrax has risen to 84, nine more than originally reported, the Atlanta-based federal agency said Friday.

"We have moved quickly to identify those who could have been exposed and they are being treated. Up to now, 84 have been identified as probably exposed," CDC spokesperson Belsie Gonzalez told Efe.

Gonzalez said there were two other cases of possible contact that have not yet been confirmed.

The workers could have been infected due to the mismanagement of live biological material at one of the CDC laboratories.

The agency said it is observing closely the workers who might have been infected and has treated them to minimize the risk of complications.

While the incident is still under investigation, authorities say the employees would have been exposed to anthrax while handling samples of live material that had not been inactivated correctly.

The workers thought the samples were inactivated and did not use the equipment for personal protection required in such cases, the CDC said.

Authorities do not believe that people outside the agency are at any risk of anthrax infection.

Anthrax can infect the skin, lungs and digestive system of those who come in contact with the substance and is considered one of the most dangerous resources of biological terrorism.

The accidental exposure was discovered on June 13 when the original bacteria samples were collected to discard as trash and traces of live bacteria were detected that had been distributed among several CDC laboratories. EFE