WHO declares Ebola outbreak in DR Congo
At least one person has died after contracting the virus in the country's north-east, the WHO says.
The Congolese health ministry had notified the WHO of a "lab-confirmed case" of Ebola, it added on Twitter.
More than 11,000 people died in the Ebola outbreak in West Africa in 2014-2015, mainly in Guinea, Sierra Leone and Liberia.
The last outbreak of Ebola in the Democratic Republic of Congo was in 2014 and killed more than 40 people.
Of the nine people suspected to have contracted the deadly virus, three died, with one case of Ebola confirmed through tests at the national laboratory in the capital Kinshasa, WHO Congo representative Allarangar Yokouide said in a statement.
People began to get sick on or after 22 April in Bas-Uele province in the country's far north, he added.
The region affected lies 1,300km (800 miles) north-east of Kinshasa, close to the border with the Central African Republic.
"It is in a very remote zone, very forested, so we are a little lucky. But we always take this very seriously," WHO Congo spokesman Eric Kabambi told Reuters news agency.
The WHO described the outbreak as "a public health crisis of international importance". ■