The World Health Organisation says the Ebola virus outbreak in Congo — which spread to Uganda — does not yet merit being declared a global emergency, but is “an extraordinary event” of deep concern.

The UN health agency convened its expert committee for the third time to assess the outbreak, which some experts say met the criteria to be designated an international emergency long ago.

This outbreak, the second-deadliest in history, has killed more than 1,400 people since it was declared in August.

At a press briefing following the meeting, Dr Preben Aavitsland, the acting chair of the committee, announced that the outbreak is “a health emergency in the Democratic Republic of the Congo” but that the situation does not yet meet the criteria for being declared a global one.

For such a declaration, an outbreak must constitute a risk to other countries and require a coordinated response.

The declaration typically triggers more funding and political attention.

Dr Aavitsland said the committee was “deeply disappointed” that WHO and the affected countries have not received the funding needed to stop the outbreak and delivered a blunt message to donors: “Step up.”

The outbreak, occurring close to the borders of Uganda, Rwanda and South Sudan, has been like no other.

Congo Ebola OutbreakPeople crossing the border have their temperature taken to check for symptoms of Ebola (Al-hadji Kudra Maliro/AP)

Mistrust has been high in a region that had never faced Ebola before and attacks by rebel groups have undermined aid efforts.

On Thursday, WHO’s emergencies chief acknowledged the agency has been unable to track the origins of nearly half of new Ebola cases in DR Congo amid the challenges, suggesting it does not know where the virus is spreading.

WHO’s expert committee has met twice previously to consider the situation in DR Congo.

In April, the UN health agency said the outbreak was of “deep concern” but officials were “moderately optimistic” it could be contained within a “foreseeable time”.