The World Health Organization (WHO) has declared the Ebola crisis in the Democratic Republic of Congo (DRC) a public health emergency of international concern.
But it stressed borders should not be closed, adding that the risk of the disease spreading outside the region was not high.
The outbreak in the DRC has killed more than 1,600 people.
This week, the first case was detected in Goma, home to more than a million.
WHO chief Tedros Adhanom Ghebreyesus told a news conference in Geneva that he had accepted the recommendations of a committee of experts which stressed there should be no restrictions on travel or trade, and no entry screening of passengers at ports or airports outside the immediate region BBC said.
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The most recent serious Ebola outbreak before this one, in West Africa, killed more than 11,000 people.
The outbreak, the second largest in history, started in August 2018 and is affecting two provinces in DRC North Kivu and Ituri.
More than 2,500 people have been infected and two-thirds of them have died.
It took 224 days for the number of cases to reach 1,000, but just a further 71 days to reach 2,000.
About 12 new cases are being reported every day.
Tackling the disease has been complicated by conflict in the region.
Since January, there have been 198 attacks against healthcare workers or Ebola treatment facilities leading to seven deaths and 58 injuries.
Another major problem has been distrust of healthcare workers leading to about a third of deaths being in the community rather than at a specialist Ebola treatment center.
It means those people are not seeking treatment and risk spreading the disease to neighbours and relatives.
There has also been difficulty tracking the spread of the virus.
A significant number of cases are coming as a surprise as those affected have not come into contact with known Ebola cases.
“We are one year into the outbreak and the situation is not getting any better,” said Trish Newport, from the charity MSF.
“It’s a complex environment with a long history of violence, of conflict, so there’s a lot of mistrust of foreigners from outside the area.
“We have to build ties and connections with the community so they trust us.”