FREETOWN - Sierra Leone has put three more districts under indefinite quarantine in a bid to fight Ebola, President Ernest Bai Koroma said in a statement, which means five of the country's 14 districts have now been isolated.

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The quarantined districts include Port Loko and Bombali in the north and Moyamba in the south, according to a statement Koroma gave late on Wednesday.

"The isolation of districts and chiefdoms will definitely pose great difficulties for our people in those districts," Koroma said. "(But) the life of everyone and the survival of our country take precedence over these difficulties."

The World Health Organisation said on Thursday the death toll for the Ebola outbreak in West Africa, the worst on record, has killed 2,917 people this year, including nearly 600 people in Sierra Leone.

The new restrictions are likely to further hamper major iron ore firms operating in Sierra Leone. Port Loko is home to London Mining's concession and African Minerals has its rail and port services there.

The move follows a three-day countrywide lockdown at the weekend that Koroma said had been a success but exposed "areas of greater challenges".