CONAKRY/GENEVA (Reuters) - Foreign mining firms have locked down operations in Guinea and pulled out some international staff, executives said on Wednesday, as the death toll from suspected cases of Ebola there hit 84.

The West African nation’s government said four new suspected cases of one of the world’s most lethal infectious diseases had been reported in the last 24 hours, bringing the total to 134.

Medical charity Medecins Sans Frontieres (MSF) has warned Guinea was facing an unprecedented epidemic of Ebola that would test weak health systems across West Africa.

Suspected cases of the disease - which has a fatality rate of up to 90 percent - have also been reported in neighboring Liberia and Sierra Leone, while Gambia said two people had been quarantined after arriving from southeastern Guinea.

The epicenter 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 aluminum 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, asking not to be named.

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

MINERS CONCERNED ABOUT CAPITAL

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

The U.N.’s World Health Organization (WHO) has so far reported 12 suspected cases and four deaths in the ocean-front city of 2 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 300 km (190 miles) away.

“Unfortunately, this one person infected both family members and health care workers when he went to Conakry for medical attention and died,” Hartl told Reuters in Geneva.

Brazilian iron ore miner Vale said its VBG joint venture with BSG Resources (BSGR) - the mining arm of Israeli billionaire Beny Steinmetz’s business conglomerate - had pulled its six international staff out of Guinea.

“The expatriates have been transferred temporarily to their home countries,” Vale said in an emailed statement in Brazil. “The local employees ... have been given leave from work until there is more accurate information about the risks of the disease.”

There has not been any official statement from the chamber of mines but the executive said mining firms had been calling each other to discuss the best response. “People are locking down camps and keeping movements to a minimum,” the executive added.

Neighboring Senegal has closed its land borders with Guinea, and countries across the region have taken precautionary measures, including banning the sale and consumption of bats, a regional delicacy but an animal believed to be a vector for the virus.