Sierra Leone's proposed countrywide "lockdown" will not help control an Ebola outbreak and could lead to the disease spreading further as cases are concealed, medical charity Doctors Without Borders (MSF) said on Saturday.

The government plans to order citizens not to leave the areas around their homes for three days from Sept. 19 in a bid to halt new infections and help health workers track down people suffering from the disease, the information ministry said on Saturday.

"It has been our experience that lockdowns and quarantines do not help control Ebola as they end up driving people underground and jeopardizing the trust between people and health providers," said the group.

"This leads to the concealment of potential cases and ends up spreading the disease further," added the group which has been helping fight the world's biggest outbreak of the disease across West Africa.

An Ebola outbreak that was first identified in Guinea in March has since spread across much of Liberia and Sierra Leone. Cases have also been registered in Nigeria and Senegal and the World Health Organization says more than 2,100 people have died.

More than six months into the crisis, weak government health systems are still failing to defeat the disease, one of the deadliest on the planet.

Shutdown aims to help trace suspected cases

The WHO says it will take months to bring Ebola under control and forecast as many as 20,000 cases.

Sierra Leone's deputy information minister, Theo Nichol, said on Saturday the three-day shutdown would make it easier for medical workers to trace suspected cases.

Doctors Without Borders

Doctors Without Borders health workers say Sierra Leone lockdown will drive people underground and lead to the concealment of possible cases. (2Tango/Reuters)

Nichol said the period may be extended if needed. A presidency official had earlier said the lockdown would last for four days.

But MSF said door-to-door screening required a high level of expertise and, even when cases were found, there were a lack of treatment centres and other facilities to take them to.

MSF reiterated its calls for nations with civilian and military biological-disaster response capacities to send equipment and teams to West Africa.

"This remains our best hope of bringing this deadly outbreak under control as quickly as possible," it said.