The US Centers for Disease Control (CDC) announced the additional transfers on Saturday after an infected US health worker arrived a Nebraska clinic from Sierra Leone on Friday.

The American television channel CNN reported the number in the latest evacuation amounted to "10 or so."

Partners in Health, a Boston-based nonprofit organization, had said on Friday that the infected person was a clinician but provided no name or gender. That patient was admitted to the National Institutes of Health clinic in Maryland.

CDC spokesman Thomas Skinner said the ten Americans subsequently transferred might have been exposed to the unidentified Ebola patient or who had experienced similar exposure.

The individuals had been transported in non-commercial aircraft and had been allotted - alongside Nebraska - to clinics in Maryland and Atlanta, the CDC said.

The individuals would undergo monitoring over a 21-day period stipulated to establish whether the virus was not present or incubating.

Ebola, a virus that can result in deadly hemorrhaging, has killed about 10,000 people since early last year in three west African nations - Sierra Leone, Liberia and Guinea.

On Thursday, the World Health Organization said the total number of cases - fatal and non-fatal - stood at 24,350.

ipj/jr (Reuters, dpa, AP)