The drugs, named REGN-EB3 and mAb114, work by attacking the Ebola virus with antibodies, neutralising its impact on human cells.

They are the “first drugs that, in a scientifically sound study, have clearly shown a significant diminution in mortality” for Ebola patients, said Dr Anthony Fauci, director of NIAID.

REGN-EB3 and mAb114 were developed using antibodies harvested from survivors of Ebola, which has killed more than 1,800 people in DR Congo in the past year.

Two other treatments, called ZMapp and Remdesivir, have been dropped from trials as they were found to be less effective.