The Democratic Republic of Congo said on Wednesday that suspected Ebola cases had been reported in a new province, highlighting the expansion of the ongoing outbreak as deaths hit 600. 

The outbreak, declared on May 15, has so far infected 1 759 people across the eastern provinces of Ituri, North Kivu and ​South Kivu, according to the government's latest situation report published Wednesday night.

But that case total does not include two cases in Kisangani, the capital of Tshopo province and one of Congo's biggest cities, the situation report said.

One of those cases is linked to the health zone of Niania in Ituri province, where the first cases were reported. But the second case "does not appear to have a geographic link" beyond Kisangani, it said.

The positive test results are in the process of being validated by confirmatory testing, after which they will be included in the official case total, it said.

Response teams have in the meantime begun strengthening surveillance, contact tracing and other containment measures in Kisangani, it said.

Reuters reported last week that Congolese health authorities were tracing people potentially exposed to Ebola in two provinces not previously affected by the outbreak: Tshopo and Haut-Uele.

The situation report published late Wednesday documented 51 new cases and 20 new deaths in the previous 24 hours.

The World Health Organization said this week that the outbreak had not yet stabilised and was still expanding as population movement fuelled transmission.