Three people have died of Ebola, and another five have tested positive for the virus in southeastern Guinea, the state health agency said, the first possible resurgence of the disease there since the world's worst outbreak in 2013-2016.

The patients fell ill with diarrhoea, vomiting and bleeding after attending a burial in Goueke sub-prefecture. The five still alive have been isolated in treatment centres, the agency ANSS said on Sunday.

It was not clear if the person buried on Feb. 1 - a nurse at the local health centre who had fallen ill - had also died of Ebola.

The last major outbreak of Ebola in West Africa started in Guinea. It went on to kill at least 11,300 people with the vast majority of cases in Guinea, Liberia and Sierra Leone.

A second round of tests is being carried out to confirm the latest Ebola diagnosis and health workers are working to trace and isolate the contacts of the cases, ANSS said.

It said Guinea would contact the World Health Organization (WHO) and other international health agencies to acquire Ebola vaccines. The vaccines have greatly improved survival rates in recent years.

"WHO is ramping up readiness & response efforts to this potential resurgence of #Ebola in West Africa, a region which suffered so much from Ebola in 2014," the agency's Regional Director for Africa Matshidiso Moeti said on Twitter.

The vaccines and improved treatments helped efforts to end the second-largest Ebola outbreak on record, which was declared over in Democratic Republic of Congo last June after nearly two years and more than 2,200 deaths.

Congo reported three new Ebola cases this month in one of the epicentres of that epidemic in eastern North Kivu province.

The Ebola virus causes severe vomiting and diarrhoea and is spread through contact with body fluids. It has a much higher death rate than COVID-19, but unlike coronavirus it is not transmitted by asymptomatic carriers. (Writing by Alessandra Prentice Editing by Gareth Jones and Frances Kerry)