Health facilities in the epicentre of an Ebola outbreak in the Democratic Republic of Congo are overwhelmed, and essential supplies are running out, the International Federation of Red Cross and Red Crescent Societies said on Monday.

More resources are urgently needed to contain the outbreak, the IFRC said, as supplies of clean water and protective equipment near depletion.

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The IFRC is appealing for 20 million Swiss francs ($25 million) to help contain the outbreak in Bulape, in the centre of Congo.

The outbreak, the country's first in three years, was declared in early September.

Congo's dense tropical forests are a natural reservoir for the Ebola virus, which causes fever, body aches and diarrhoea. It can linger in the body of survivors and resurface years later.

"Health facilities are overwhelmed, essential supplies are not available, and the area is without power," Ariel Kestens, IFRC Head of Delegation in Kinshasa, said in a statement.

The World Health Organization said last week that 48 confirmed and probable cases of Ebola had been reported in Congo and that 31 people with the virus had died.

The main isolation centre in Bulape has few spaces for patients, and the only treatment centre is already at 119% capacity, the IFRC said.