Almost 7,000 people have died in the Ebola outbreak, with infection rates soaring in Sierra Leone according to the World Health Organisation.

More than 1,200 were added to the death toll in west Africa since WHO reported on Wednesday.

While the virus is being contained and reduced in affected countries such as Liberia and Guinea, there is between 400 to 500 new cases each week in Sierra Leone, putting increasing pressure on bed space in hospitals.

Sixty five per cent of the country's new infections are centred in the Freetown capital, surrounding areas and the northern Port Loko district, Anthony Banbury, head of the UN Mission for Ebola Emergency Response, told AP.

"The critical gap right now in those locations are beds. It's as simple that: We need more beds,'' said Banbury, who spoke by telephone from Ghana, where the mission is headquartered.

The UN expected the end of the outbreak would be in sight by 1 December.

"As long as there's one person with Ebola out there, then the crisis isn't over and Ebola is a risk to the people of that community, that country, this sub-region, this continent, this world,'' Banbury added.

"Our goal and what we will achieve is getting it down to zero, but there's no doubt it's going to be a long, hard fight."