World Health Organisation (WHO) spokesman Gregory Hartl said by email on Friday one man who died in a suspected case of Ebola in Nigeria, escalating fears and the quarantine of 10 others, did not have the deadly virus.
A man died shortly after being admitted to hospital, the nurses who attended the patient are among the people who have been quarantined.
Hartl wrote "[The] dead person tested negative for Ebola. So this person is not going to be the source of an Ebola event."
Hartl also said, a laboratory test confirmed the dead person did not have Ebola or Lassa fever.
On Wednesday, the three countries most affected by the disease -Guinea, Sierra Leone and Liberia- announced a week of no new cases since the outbreak of the disease in 2014.
Last year in Nigeria, nine people have been reported to being infected with Ebola, seven of them have died.
Ebola first appeared in Nigeria in 2014 in the airport of Lagos where a Nigerian businessman had collapsed suddenly.
Official figures show that the west African outbreak of Ebola has killed more than 11,000 of 28,000 people since first emerging in December 2013 in Guinea, with Liberia being hit the hardest.
Experts acknowledge that poor monitoring carried out in the past, especially early in the outbreak, means that the real death toll could be significantly higher.