An Ebola epidemic which has already killed dozens of people in Guinea's southern forests has spread to the capital Conakry, AFP reports according to the United Nations Children's Fund.
"At least 59 out of 80 who contracted Ebola across the West African country have died so far. Over the past few days, the deadly haemorrhagic fever has quickly spread from the communities of Macenta, Gueckedou, and Kissidougou to the capital, Conakry," UNICEF said in a statement emailed to AFP.
Conakry, a vast, sprawling port city on Guinea's Atlantic coast, is estimated to have a population of between 1.5 and two million.
To date, no treatment or vaccine is available for Ebola, which kills between 25 and 90 percent of those who fall sick, depending on the strain of the virus, according to the World Health Organisation.
The disease is transmitted by direct contact with blood, faeces or sweat, or by sexual contact or unprotected handling of contaminated corpses.
UNICEF said at least three victims of the outbreak, which began on February 9, were children.
"This outbreak is particularly devastating because medical staff are among the first victims, so far it has killed at least eight health workers who have been in contact with infected patients, hindering the response and threatening normal care in a country already lacking in medical personnel," UNICEF said.
The organisation said it had rushed five tonnes of aid, including medical supplies, to the most affected areas in Guinea's south.
"In Guinea, a country with a weak medical infrastructure, an outbreak like this can be devastating," said the organisation's Guinea representative, Mohamed Ag Ayoya.
"UNICEF has pre-positioned supplies and stepped up communication on the ground to inform and sensitise medical staff and the population on how to avoid contracting Ebola."
The organisation urged Guineans not to attend funerals wherever possible and to avoid all contact with the sick and the dead.
Ebola, one of the world's most virulent diseases, was first discovered in the Democratic Republic of Congo (DRC) in 1976 and the country has had eight outbreaks.
The most recent epidemic, also in the DRC, infected 62 people and left 34 dead between May and November 2012, according to the country's health ministry.
There are fears it could be used in a biological weapons attack.
According to researchers, the virus multiplies quickly, overwhelming the immune system's ability to fight the infection.
Medical aid group Doctors Without Borders (MSF) said in a statement on Saturday it had set up isolation units for suspected cases in the southern region of Nzerekore and was seeking out people who may have had contacts with the infected.