North Sierra Leone in five-day Ebola lockdown

© Evan Schneider UN/AFP/File

A medic listens as UN Secretary General Ban Ki-Moon gives a speech during his visit an Ebola treatment unit in Freetown on December 19, 2014.

Deputy communication minister Theo Nicol said "the lockdown for five days... is meant for us to get an accurate picture of the situation," adding: "Other districts will carry on with their own individual lockdown after this if they deemed it necessary."

Ebola has killed more than 7,500 people, almost all of them in west Africa.

Sierra Leone, Liberia and Guinea are the three nations worst-hit by the epidemic, and Sierra Leone recently overtook Liberia as the country with the highest number of Ebola infections.

Kamara said shops and markets would be closed throughout the period, and "no unauthorised vehicles or motorcycle taxis" would be allowed to circulate "except those officially assigned to Ebola-related assignments."

Among "key objectives" is to allow health workers to identify patients, Kamara said.

Sierra Leone declared a state of emergency on July 31 after the Ebola outbreak and imposed restrictions on the movement of people.

As of Wednesday six of the country's 14 departments have these restrictions in place.

On December 12, the government announced a restriction on large Christmas and New Year gatherings.

Several residents in the country's north told AFP by telephone that locals had largely been conforming to the new strictures.

'Bleak Christmas'

"The streets are deserted and people are staying indoors or sitting in their backyards," said Felix Koroma, in Makeni, in the district of Bombali.

"Although the district is predominantly Muslim, it is traditional for Muslims to join with Christians to celebrate Christmas but from what I can deduce, its going to be a bleak occasion," he added.

Sarah Tucker, in Port Loko district said the only activity she could see was "medics moving from house-to-house" looking to remove the sick from their homes.

But some residents said they had not been given adequate warning to stockpile supplies.

"The notice given was too short and it was difficult for us to keep food in the house," a resident of Magburaka, in Tonkolili, who wished to remain anonymous, told AFP.

"The lockdown is good but we are worried over what to eat until it ends."

The lockdown came after it was announced that a fourth member of the UN mission in neighbouring Liberia had been hospitalised after testing positive for the virus.

The UN employee tested positive on Tuesday and was immediately transferred to an Ebola treatment unit, Karin Landgren, the special representative of UN chief Ban Ki-moon, said.

"UNMIL is taking all necessary measures to mitigate any possible further transmission - - both within the mission and beyond," Landgren said, referring to the United Nations Mission in Liberia.

A UN statement said its mission had stepped up surveillance "to ensure that all people who came into contact with the staff member while symptomatic are assessed and quarantined".

Liberia tops the number of Ebola deaths in the world with 3,376 fatalities but has seen a clear decrease of new transmissions in the past month.