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.