Following earlier denials, Liberia has admitted that 17 suspected Ebola patients are "missing" after a health centre in the capital was looted.
The government had sought to reassure people, saying all the patients had been moved to another health facility.
But Information Minister Lewis Brown told the BBC that 17 inmates had gone "back into their communities".
The World Health Organization (WHO) has called for exit screenings on all travellers from affected countries.
It wants checks at airports, sea ports and major land crossings.