Scientists are a step closer to finding the first effective treatments for the deadly Ebola haemorrhagic fever after two ­potential drugs showed survival rate of as much as 90 percent in a clinical trial in the Democratic Republic of the Congo (DRC).

Two experimental drugs - Regeneron's REGN-EB3 and a monoclonal antibody called mAb114 - were both developed using antibodies harvested from survivors of Ebola infection.

The treatments are now going to be offered to all patients in DRC, according to US National Institute of Allergy and Infectious Diseases.

They showed "clearly better" results in patients in a trial of four potential treatments being conducted during the world's second-largest Ebola outbreak in history, now entering its second year in DRC.

The drugs improved survival rates from the disease more than two other treatments being tested - ZMapp, made by Mapp Biopharmaceutical, and Remdesivir, made by Gilead Sciences - and those products will be now dropped, said Anthony Fauci, one of the researchers co-leading the trial.

The agency said 49 percent of the ­patients on ZMapp and 53 percent on remdesivir died in the study. In comparison, 29 percent of the patients on REGN-EB3 and 34 percent on mAb-114 died.

Fauci, director of the US National Institute of Allergy and Infectious Diseases, told reporters in a telebriefing the results were "very good news" for the fight against Ebola.

"What this means is that we do now have what look like [two] treatments for a disease for which not long ago we really had no approach at all," he said.

The agency said of the patients who were brought into treatment centers with low levels of virus detected in their blood, 94 percent who got REGN-EB3 and 89 percent on mAb114 survived.

In comparison, two-thirds of the patients who got remdesivir and nearly three-fourths on ZMapp survived.

Ebola has been spreading in eastern DRC since August 2018 in an outbreak that has now become the second-largest, killing at least 1,800 people. Efforts to control it have been hampered by militia violence and some local resistance to outside help.

A vast Ebola outbreak in West Africa became the world's largest ever when it spread through Guinea, Liberia and ­Sierra Leone from 2013 to 2016 and killed more than 11,300 people.