Sierra Leone has confirmed its first death from Ebola, with several more suspected to have succumbed to the deadly virus that swept across neighbouring Guinea earlier this year.

"I can categorically confirm that the Ebola sickness has materialised," said health ministry official Amara Jambai on Monday.

"Preliminary information received from the field indicates that one laboratory-confirmed case and five community deaths have been reported from Koindu chiefdom," the World Health Organisation said in a statement on its website.

Jambai initially said four cases of Ebola fever had been identified, but later clarified that while four people had died, only one person had so far been confirmed to have had the virus, the AFP news agency reported.

"Of the four deaths only one has been confirmed as dying from Ebola after two independent tests at the Kenema Laboratory Centre. The cause of death of the other three is still being investigated," he said.

More patients

Jambai said 11 people with acute diarrhoea and vomiting had been admitted to the Koindu community health centre in a region bordering southern Guinea.

Four people had died and five were responding to treatment.

Ebola has killed more than 100 people in neighbouring Guinea and Liberia since March, and has a fatality rate of up to 90 percent.

It is one of a handful of similar fevers that cause vomiting, diarrhoea, muscle pain, and in severe cases, organ failure and unstoppable internal bleeding.

It can be transmitted by blood and other bodily fluids, as well as the handling of contaminated corpses or infected animals, known to be vectors of the disease.

The WHO has described the region's first Ebola outbreak as one of the most challenging outbreaks it has faced.