A three-day lockdown announced by Sierra Leone to combat Ebola will not help contain the virus, medical charity Medecins Sans Frontieres (MSF) says.
The charity said a lockdown would force people underground, destroy trust between doctors and the public and ultimately help spread the disease.
Sierra Leone officials say the measure, due to begin on 19 September, will let health workers isolate new cases.
About 2,100 people in Sierra Leone, Liberia and Guinea have so far died.
MSF, whose staff are helping to tackle the outbreak, said in a statement that quarantines and lockdowns “end up driving people underground and jeopardising the trust between people and health providers”.
“This leads to the concealment of potential cases and ends up spreading the disease further,” the group said.
Sierra Leonean officials earlier said more than 20,000 people would be deployed to make sure residents stayed indoors.
Health Ministry spokesman Sidie Yahya Tunis told the BBC he did not expect the public to object.
“You follow or else you’ll be breaking the law. If you disobey then you are disobeying the president,” he said.
The BBC’s West Africa correspondent Thomas Fessy says the Sierra Leone population’s willingness to obey will be key for the plan to succeed.
A forcible implementation is likely to raise human rights issues and could potentially spark violent demonstrations, he says.
Last month, Liberia sealed off a large slum in the capital, Monrovia, for more than a week in an attempt to contain the virus.
The disease infects humans through close contact with infected animals, including chimpanzees, fruit bats and forest antelope.
It then spreads between humans by direct contact with infected blood, bodily fluids or organs, or indirectly through contact with contaminated environments.
Officials in Nigeria have meanwhile decided to reopen schools in the country from 22 September. They were closed as a precaution to prevent the spread of the virus.
Ebola virus disease (EVD)
- Symptoms include high fever, bleeding and central nervous system damage
- Spread by body fluids, such as blood and saliva
- Fatality rate can reach 90% – but current outbreak has mortality rate of about 55%
- Incubation period is two to 21 days
- There is no proven vaccine or cure
- Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery
- Fruit bats, a delicacy for some West Africans, are considered to be virus’s natural host
Separately, a US doctor infected with Ebola is being treated in a Nebraska hospital after evacuation from Liberia.
Rick Sacra, 51, was described as sick but stable. He is the third American aid worker infected. The other two recovered after treatment in Atlanta.
On Friday, the WHO announced that the blood of patients who recovered from Ebola should be used to treat others.
People produce antibodies in the blood in an attempt to fight off an Ebola infection. The antibodies may be able to help a sick patient’s immune system if they are transferred.
However, large scale data on the effectiveness of the therapy is lacking.