The UN’s Ebola mission chief says the world is falling behind in the race to contain the virus, with thousands of new cases predicted by December.
“It is running faster than us, and it is winning the race,” Anthony Banbury told the UN Security Council.
Meanwhile, more questions are being asked in the US about how a nurse in Texas became infected with the virus.
The World Health Organization (WHO) says 4,447 people have died from the outbreak, mainly in West Africa.
Sierra Leone, Liberia and Guinea have been hardest hit by the outbreak, which began in December 2013 but was confirmed in March.
US President Barack Obama said on Tuesday that “the world as a whole is not doing enough” to contain the Ebola threat.
He will discuss the Ebola crisis in a video conference on Wednesday with British, French, German and Italian leaders, the White House says.
Mr Banbury issued a stern warning on Tuesday – telling the UN Security Council by video-link from West Africa that if Ebola was not stopped now, the world would “face an entirely unprecedented situation for which we do not have a plan”.
“If we do not get ahead of the crisis, if we do not reach our targets and the number of people with Ebola rises dramatically as some have predicted, the plan we have is not scalable to the size of such a new crisis,” he said.
He called for more money to build treatment centres and more medical personnel to staff them.
It follows the WHO’s latest projections suggesting the infection rate could reach 5,000 to 10,000 new cases a week within two months if global efforts to combat the spread of infection were not stepped up.
There have been 8,914 cases overall, including the fatal cases, and the WHO says it expects this number to top 9,000 by the end of the week.
The WHO estimates its figures by taking the numbers of confirmed cases and multiplying them – from Guinea by 1.5, from Sierra Leone by 2 and from Liberia by 2.5 – to account for under-reporting.
WHO assistant director-general Bruce Aylward said on Tuesday that the rate of infections appeared to be slowing in the “historic epicentre” of the outbreak, but warned that it was too early to read this as success.
Separately, nurses at a hospital in Texas where a colleague contracted the virus from a Liberian patient who died of Ebola say they worked for days without protective clothing and received little guidance on how to prevent the spread of the virus.
It comes after the head of the US Centers for Disease Control, Thomas Frieden, said there had been a breach of protocol by health workers that led to the nurse becoming infected.
“The CDC is saying that protocols were breached, but the nurses are saying there were no protocols,” the head of the national nurses union, Roseann DeMoro, told reporters.