The World Health Organisation on Sunday declared the outbreak a public health emergency of international concern because of the high risk the disease could spread further beyond DR Congo's borders after two cases were confirmed in Kampala, the capital of neighbouring Uganda.
The outbreak is suspected to have killed about 80 people in recent weeks, with eight cases confirmed by laboratory testing and 246 suspected cases reported in eastern DR Congo's Ituri province.
Another case was confirmed in neighbouring North Kivu province's capital, Goma, according to the M23 rebels who control the city.
The US Centers for Disease Control and Prevention (CDC) also said on Sunday that it was supporting partners withdrawing a small number of directly affected US citizens.
A delegation led by DR Congo Health Minister Samuel Roger Kamba arrived in Ituri's capital Bunia on Sunday with tents to set up treatment centres to support strained local hospitals.
"This is not a mystical disease," he told Reuters.
"Make yourself known so that you can be taken care of and so that we can prevent the disease from spreading."
WHO's representative in DR Congo, Anne Ancia, said the world body had emptied its stocks of protective equipment in the capital Kinshasa and was preparing a cargo plane to bring additional supplies from a depot in Kenya.
The European Centre for Disease Prevention and Control said on Monday it was deploying an expert to its African counterpart's headquarters in Ethiopia to support operational planning, and the US CDC said it planned to send more people to its offices in the DR Congo and Uganda.
On Monday, the US embassy in Uganda said it had temporarily paused all visa services in Uganda in light of the Ebola virus outbreak there, effectively restricting travel.
And a Reuters witness said DR Congolese people trying to cross into Rwanda from Bukavu were stopped by authorities at the border.
The current outbreak is caused by the Bundibugyo virus, which unlike the more common Zaire strain of Ebola, has no approved virus-specific therapeutics or vaccine.
An outbreak of the Zaire strain from 2018-2020 in North Kivu and Ituri provinces was the second deadliest on record, killing nearly 2300 people.
The response to that outbreak was complicated by widespread armed violence in eastern DR Congo that continues today.
Jean Pierre Badombo, the former mayor of Mongbwalu, a mining town in Ituri at the epicentre of the outbreak, said people started falling ill in April after a large open-casket funeral procession arrived from Bunia.
"After that, we experienced a cascade of deaths," he said.
The WHO has said it was informed of an unknown illness with high mortality in Mongbwalu on May 5, including four health workers who had died within four days, and dispatched a rapid response team.
Several subsequent missteps, including an initial failure by personnel in Bunia to escalate samples for further testing after they came back negative for the Zaire strain, meant the virus was not detected until May 14, DR Congolese health officials told Reuters.
An outbreak was declared the next day.
Lievin Bangali, IRC's senior health coordinator in DR Congo, said declining funding from international donors had also weakened disease detection.
"When surveillance networks break down, dangerous diseases like Ebola are able to spread further and faster before communities and health workers can respond," he said.
DR Congo has experienced 17 outbreaks of Ebola since the virus was first identified in the country in 1976.
The disease spreads through direct contact with the bodily fluids of infected persons or contaminated materials.
According to WHO, the average fatality rate from Ebola is about 50 per cent, varying from 25 per cent to 90 per cent in past outbreaks.
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