As transport companies suspend services, cutting off the region, governments and economists have warned that the worst outbreak of the hemorrhagic Ebola fever on record could crush the fragile economic gains made in Sierra Leone and Liberia following a decade of civil war in the 1990s.

Air France, the French network of Air France-KLM said on Wednesday it had suspended flights to Sierra Leone after advice from the French government. France did not recommend suspending flights to Nigeria or Guinea.

"Revenues are down, foreign exchange levels are down, markets are not functioning, airlines are not coming in, projects are being canceled, business people have left; that is very, very damaging," African Development Bank (AfDB) chief Donald Kaberuka said in an interview late on Tuesday.

"The numbers I have had vary from one percent to four percent of GDP. That is a lot in a country with a GDP of US$6 billion," Kaberuka said, when asked to quantify the impact.

Liberia has already said it would have to lower its 2014 growth forecast, without giving a new one.

Sierra Leone Deputy Minister of Mineral Resources Abdul Ignosis Koroma also told Reuters the government would miss its target of exporting $200 million in diamonds this year because of the Ebola outbreak, versus $186 million last year.

"There is no way the government can reach this amount since the districts where diamonds are mined are not Ebola-free," Koroma said.

He said miners were too afraid to go to alluvial diamonds pits in the Ebola-stricken east and tough border controls to curb the spread of the virus were also hurting the trade.

Iron ore miner London Mining, whose only operating mine is in Sierra Leone, said recently that Ebola could hurt its production this year. Several international companies in the region have pulled out expatriate staff in recent weeks.

The AfDB this week donated $60 million to help train medical workers and purchase supplies to fight the outbreak, which has already killed more than 1,400 people, mostly in Guinea, Sierra Leone and Liberia.

Some $15 million will be disbursed in September, Kaberuka said during a press conference in Liberia on Wednesday.

The disease also has a toehold in Africa's most populous country Nigeria, where it has killed five people, but authorities there say the outbreak has been contained so far.

"Nigeria is still at risk of Ebola because we still have one case and from this one case the risk of spread is still there," Nigerian Health Minister Onyebuchi Chukwu said on Wednesday.

MEDICAL EVIDENCE VERSUS POLITICS

Kaberuka described the health care systems of the affected countries as "overloaded", adding that he hoped the AfDB donation would stop money being diverted away from other programmes such as education and agriculture.

Echoing comments from governments of the Ebola-affected countries, he said travel and trade restrictions imposed by airlines, shipping firms and neighbouring economies were increasing the economic hardship.

"I understand the countries which are posing restrictions ... but let us only do so based on medical evidence and not on political imperatives," said Kaberuka.

The World Health Organization has repeatedly advised against such bans, warning they could cause food and supply shortages.

Brussels Airlines said on Wednesday it had resumed flying to Liberia, Sierra Leone and Guinea after it was forced to suspend the routes over the weekend after Senegal refused to allow it to change its flight crews there.

The airline, in which Germany's Lufthansa owns a 45 percent stake, said there were passenger waiting lists in all three countries and around 50 tonnes worth of emergency medical supplies waiting at Brussels airport to be transported.

"There is indeed a strong need for airline services to the countries," Brussels Airlines spokesman Geert Sciot told Reuters. "We're trying under extremely difficult circumstances to fill that role."

Democratic Republic of Congo announced on Sunday a separate outbreak of Ebola in its remote northwestern province of Equateur and said it had killed at least 13 people. It was Congo's seventh outbreak since the disease - believed to be carried by bush animals - was first detected there in 1976.

The first case in the new outbreak appeared to be a pregnant woman in the village of Ikanamongo who died on August 11 after butchering a bush animal, the WHO said on Wednesday.

"At this time, it is believed that the outbreak in DRC is unrelated to the ongoing outbreak in west Africa," the U.N. agency said in a statement, adding that samples had been sent to laboratories to determine the specific strain of the virus.

It said it had assembled a rapid response team and was ready to assist Congo if needed.