Foreign mining firms have locked down operations in Guinea and pulled out some international staff as the death toll from suspected cases of Ebola there hit 83.

Five new suspected infections were reported in the last 24 hours, according to the UN’s World Health Organisation, bringing the total to 127.

Medical charity Médecins Sans Frontières has warned of an unprecedented epidemic that is testing weak health systems across West Africa.

Suspected cases of one of the world's most lethal infectious diseases have also been reported in neighbouring Liberia and Sierra Leone.

The epicentre of Guinea's two-month old outbreak has been in the southeast, close to its main iron ore reserves.

The country is also the world's top exporter of Bauxite, the raw material used in aluminium production, and has rich deposits gold.

"Everyone is practicing precautionary strict hygiene but there has been no real impact on production so far," a senior executive at a mining company told Reuters.

The executive said he had been placed on extended leave, while other companies were preventing people from entering or leaving their mines.

"Firms are more concerned by what is happening in the densely populated capital Conakry than in remote mining sites in the interior, where controls are easier to put in place,” he added.

The WHO has reported 12 suspected cases and four deaths in the ocean-front city of two million people.

WHO spokesman Gregory Hartl, said all the cases in Conakry were linked to one man who came from the central Guinean town of Dobala, about 300km away.

"Unfortunately, this one person infected both family members and health care workers when he went to Conakry for medical attention and died," Mr Hartl said.