Sierra Leone was preparing on Thursday for an unprecedented three-day nationwide shutdown to contain the deadly spread of the Ebola virus in a controversial move experts claim could worsen the epidemic.

The population of six million will be confined to their homes from midnight (0000 GMT) as almost 30,000 volunteers go door-to-door to hand out soap and information, in an exercise that could lead to scores more patients and bodies being discovered in people's homes.

"Rain or shine, the shutdown exercise is going to go ahead. During the three days... the job is going to get done," said Steven Gaojia, head of the government's emergency Ebola operation centre.

The worst-ever outbreak of the virus has claimed more than 550 lives in Sierra Leone, one of three countries at the epicentre of the epidemic which has so far killed some 2,600.

"Ose to Ose Ebola Tok" -- "House-to-House Ebola Talk" in the widely-spoken Krio language -- will see more than 7,000 volunteer teams of four visiting the country's 1.5 million homes.

A health worker, wearing Personal Protective Equipment, stands inside the high-risk area at Elwa hospital in Monrovia on September 7, 2014 Dominique Faget, AFP/File

They will hand out bars of soap and educate locals on how to prevent infection, as well as setting up "neighbourhood watch"-style community Ebola surveillance teams.

The government has said the teams will not enter people's homes but will call emergency services to deal with patients or bodies of which they become aware.

Extra beds have been set up at schools and hospitals across the country, including 200 in and around Freetown, with the government projecting an upsurge in cases of up to 20 percent as new patients are discovered.

- Shutdown 'could backfire badly' -

The director of the operations of Medecins Sans Frontieres, Brice de la Vingue (R-L), and medical directors Bertrand Draguez and Annette Heinzelmann give a press conference on September 18, 2014 in Paris Eric Feferberg, AFP

Health experts have criticised the shutdown, arguing that coercive measures to stem the epidemic, such as confining people to their homes, could backfire badly and would be extremely hard to implement effectively.

Doctors Without Borders (MSF) warned that lockdowns may end up driving people underground "and jeopardise the trust between people and health providers".

However, the government was at pains to emphasise that it was not a "curfew", and that people would be allowed out for essential business, such as collecting water.

An ambulance is parked in front of the Kenema government hospital, in Sierra Leone, on August 16, 2014 Carl de Souza, AFP/File

Health workers, the emergency services and other security forces will be exempt, along with the media and other professionals deemed key workers, while air passengers have been given special dispensation to get to Freetown's airport.

Gaojia said people would also be allowed to visit mosques and churches after 6:00 pm, adding that "these institutions must be nearby... just walking distance".

The president was due to launch the shutdown in a televised address to the nation on Thursday evening which he has asked tribal chiefs to repeat across the country.

- Ebola ship turned away -

The lockdown has broadly been welcomed by community leaders and residents of Freetown.

Locals walk in a market in Kenema, Sierra Leone, on August 16, 2014 Carl de Souza, AFP/File

"We shall be praying that the operation will end the scourge. We support the government," said 60-year-old Samuel Johnson, a father-of-three who recently lost a daughter to Ebola.

News of the campaign has led to traffic gridlock in Freetown amid a flurry of last-minute shopping, with large crowds thronging the streets in search of cooking oil, rice and other essentials.

Ebola fever can fell its victims within days, causing severe muscle pain, vomiting, diarrhoea and -- in some cases -- unstoppable internal and external bleeding.

Sierra Leone had been due to carry out a nationwide census in December but the government has announced on its website a postponement until April next year.

United Nations Secretary-General Ban Ki-moon said he would be setting up a mission within the region -- but outside of the worst-hit countries -- to combat the epidemic.

Meanwhile the UN Security Council was due to open an emergency session later Thursday to adopt a resolution describing the outbreak as a threat to international peace and stability.

It would also call on nations to lift travel and border restrictions imposed as a result of the outbreak while asking airlines and shipping companies to maintain their links with affected countries.

US President Barack Obama has pledged to send 3,000 military personnel to west Africa to combat the epidemic, and an initial deployment of around 20 soldiers arrived in Liberia on Thursday, an airport source said.

The first French Ebola patient -- a female volunteer who contracted the killer virus while on assignment in Liberia -- was due to be flown home on Thursday, according to MSF.

Malta turned away a ship from Guinea carrying a suspected Ebola case despite a request from its captain for assistance for the sick passenger.

Prime Minister Joseph Muscat said it was "morally and legally correct" to have prevented the ship from entering Maltese waters late Wednesday.

The Filippino passenger was taken in by Italy, and an initial medical assessment suggested he has hepatitis, port authorities in Sicily said.

Meanwhile Guinea said five people were missing following a violent protest against officials leading an awareness campaign on the Ebola outbreak on Tuesday.