Rwanda has restricted movement across its border with the DR Congo, where an Ebola outbreak has killed more than 1,800 people in the past year.
Parts of the border were closed after a third case of Ebola was identified in the Congolese border city of Goma, where two people have already died.
At least 2,700 people have been infected in the worst Ebola outbreak in the country’s history.
Tackling the disease has been complicated by conflict in the region.
About 12 new cases are being reported every day in the Democratic Republic of Congo, the World Health Organization (WHO) reports.
The biggest crossing point between the two countries was reopened after 12 hours, while a smaller one was expected to reopen later on Thursday.
The closure had been ordered to “avoid unnecessary crossings” to Goma, said Gilbert Habayarimana, the mayor of Rubavu district in western Rwanda, which borders Goma.
The Congolese presidency said it “deplore[d] this decision, which runs counter to the advice of the WHO,” which had warned against trying to contain the virus by closing borders or restricting travel or trade.
Goma, home to two million people, is the capital of North Kivu, one of the two provinces in the DR Congo which have borne the brunt of the epidemic.
The city lies just across the border from the Rwandan city of Gisenyi, which has a population of around 85,000. Many residents cross the frontier for work and other activities – although illegal routes are also used.
“The closure is terrible for me. Yes, Ebola is a terrible thing, but living is what matters most,” Ernest Mvuyekure, a builder who works in Goma, told the BBC. “I’m more afraid of hunger than Ebola.”
Claudine Uwitonze, who works in both Gisenyi and Goma, said: “I’m so shocked now, because my life depends on DR Congo. I’m afraid I’m going to die of hunger because I have nothing else to do.”
A third case of Ebola has been confirmed in Goma, raising fears the virus could spread in the densely populated city.
The patient is the daughter of an artisanal miner who died on Wednesday. He had come from Ituri, the other province where many cases have been confirmed.
The other victim in Goma was a priest who died last month.
Efforts to control the outbreak have been hampered by violence against healthcare workers or Ebola treatment facilities. Seven people have been killed and 58 injured in 198 attacks this year.
Another major problem has been distrust of healthcare workers . As a result, about a third of deaths have not been at specialist treatment centres, but in the community, where there is a greater risk of the disease spreading to neighbours and relatives.
Last week, the WHO designated the outbreak of Ebola a global health emergency, its highest level of alarm.
The designation has only been used four times previously, including during the Ebola epidemic that killed more than 11,000 people in West Africa between 2014 and 2016.
The WHO has also said it has insufficient money to tackle the problem. It had estimated that it needed $98m (£81m) to tackle the outbreak between February and July, but it faced a shortfall of $54m.
Yes, there is. It is 99% effective and more than 161,000 people have received it.
However, not everybody is vaccinated – only those who come into direct contact with an Ebola patient, and people who come into contact with them. And some of those people refuse to take it.
People give a variety of reasons for not taking the vaccine, including:
The vaccine, made by Merck, was developed during the epidemic in West Africa and has been available throughout the latest outbreak.
It has proven effective but is in relatively short supply, so the WHO recommended a second vaccine made by Johnson & Johnson to complement it.
But DR Congo’s Health Minister Oly Ilunga complained that the Congolese were being treated as “subjects of experimentation”, according to Reuters news agency, and he resigned over the issue.