Guinea, Liberia and Sierra Leone need a further $696 million in donor funding to rebuild their battered health services over the next two years in the wake of the deadly Ebola epidemic, senior World Health Organization (WHO) officials said on Monday.

WHO Assistant Director General for Health Systems and Innovation Marie-Paule Kieny said that donors had pledged $1.4 billion of an estimated $2.1 billion required by the three countries before December 2017.

U.N. Secretary-General Ban Ki-moon will host an international Ebola recovery conference in New York on Friday to raise additional funds for reconstruction.

More than 500 healthcare staff are among the over 11,200 people killed in West Africa by the worst recorded outbreak of the hemorrhagic fever, which erupted in Guinea in December 2013 and continues to claim lives.

"Full recovery in the three countries will not happen if we don't strengthen the health system," Kieny told a conference call with journalists. She said additional funding would also be required after 2017.

Even before Ebola struck, Guinea, Liberia and Sierra Leone had some of the poorest healthcare systems in the world, but the damage inflicted by the outbreak has left them more vulnerable than ever, officials say.

In Guinea, WHO officials have reported a drastic increase in deaths from malaria and measles. Before the crisis, the country's annual healthcare spending stood at just $7 per person in 2013, one of the lowest rates in the world.

Pre-Ebola healthcare expenditure in Liberia and Sierra Leone was little better at $14 and $11 per person respectively, well below the WHO's recommended minimum of $84 per person per year.

The re-emergence of Ebola in Liberia last week, nearly two months after it was declared free of the virus, has stoked fears that it may take longer than expected to defeat the epidemic.

Kieny said it was too soon to say how the three new cases in Liberia - one of whom has died - became infected. Tests are being carried out by the Liberian government and international health agencies.

The European Union on Monday approved 1.15 billion euros in aid for West Africa through to 2020, nearly doubling its previous commitment to a region that is a major source of migrants seeking to enter Europe. – Reuters