Sierra Leone said on Tuesday it had wrongly reported Ebola as the cause of a baby's death in a part of west African country which had been declared free of the virus weeks ago.

Villagers in the eastern district of Kailahun were dismayed when the government said on Monday a nine-month-old boy had tested positive after his death, more then three months after the last confirmed Ebola case.

The National Ebola Response Centre (NERC) said in a statement however an investigation had found that the "child in question is not an Ebola case as the sample in question is not from the child".

It did not say how the error had happened but concluded that there was "no evidence to suggest that there is an ongoing Ebola transmission in Kailahun".

It ordered the immediate end of quarantine measures imposed on a number of health workers at the hospital where the infant was treated and around 30 family members and other villagers.

NERC said a investigation would determine whether "a genuine error" or sabotage was behind the mix-up.

One of the deadliest viruses known to man, Ebola is spread through direct contact with the bodily fluids of an infected person showing symptoms such as fever or vomiting.

Residents in Kailahun had insisted that the positive test result was a mistake, as none of the baby's family had tested positive.

"If it was not for the current restrictions on parades, we would have organised a carnival to welcome the news," said Salia Carter, an official in the Njaluahun tribal chiefdom.

Administrative areas such as counties and districts are declared "Ebola-free" by local authorities and the World Health Organization (WHO) once they have gone 42 days—twice the maximum incubation period of the virus—with no new cases.

Kailahun had gone 111 days with no cases before Monday and will regain its "Ebola-free" status, according to local officials.

The epidemic has killed more than 10,000 people since it emerged in the forests of southern Guinea in December 2013 and spread to Liberia and then Sierra Leone.

Sierra Leone reported its first case in Kailahun, which borders Guinea, in May last year and the epidemic quickly spread throughout the country, with around 12,000 cases so far leading to more than 3,800 deaths.