Guinea announced on Monday that samples taken from three suspected cases of Ebola, which led to two deaths in the capital Conakry, had tested negative for the virus.
"The Pasteur Institute in Dakar worked urgently all last night on samples taken from suspected cases here in Conakry which were all negative," said Sakoba Keita, the health ministry's chief disease prevention officer.
"So for now, there's no Ebola in Conakry, but haemorrhagic fever whose nature remains to be determined."
Medics and aid workers are battling to contain west Africa's first outbreak of the deadly Ebola virus, which has killed dozens of people in Guinea's southern forest region.
UNICEF said in a statement on Sunday that "the deadly haemorrhagic fever (Ebola) has quickly spread from the communities of Macenta, Gueckedou, and Kissidougou to the capital, Conakry".
Keita said however the Pasteur Institute was still working on identifying the virus behind the fever cases in the capital and would know more "in the coming hours".