PRETORIA, September 18. /ITAR-TASS/. The government of Sierra Leone announced on Thursday a three-day nationwide lockdown campaign to contain the spread of the deadly Ebola virus that has already claimed more than 500 lives in this West African country.

The lockdown will start at 12am on Friday as 20,000 health workers and volunteers will go from house to house to identify unreported Ebola cases.

However, a number of health experts warned that these measures could backfire and would not help to control the disease outbreak in the nation of six million.

Jean-Herve Bradol, former director of medical aid group Medecins sans Frontieres (Doctors Without Borders), said that one of Africa's poorest countries "doesn't have the capacity to visit every household in just three days".

Joseph Amon, health director at Human Rights Watch, said that "quarantines and other rights-abusive measures can undermine efforts to contain the Ebola epidemic.” “The better approach is to ensure that people have access to health information and care," he said.

The current Ebola outbreak has so far killed more than 2,500 people in Sierra Leone, Liberia and Guinea, and the World Health Organization (WHO) on Tuesday warned that the outbreak’s death toll could reach 20,000.