Sierra Leone began a quarantine of more than one million people Thursday in the largest lockdown in west Africa’s deadly Ebola outbreak, as world leaders met to discuss the crisis at the United Nations.

The northern districts of Port Loko and Bombali were to be closed off along with the southern district of Moyamba — effectively sealing in around 1.2 million people.

With the eastern districts of Kenema and Kailahun already under quarantine, more than a third of the population of six million, in five of the nation’s 14 districts, now finds itself unable to move freely.

“The isolation of districts and chiefdoms will definitely pose great difficulty but the lives of everyone and the survival of our country takes precedence over these difficulties,” President Ernest Bai Koroma told the nation in a televised address late Wednesday.

“These are trying moments for everyone in the country.”

The deadliest Ebola epidemic on record has infected more than 6,200 people in west Africa and killed nearly half of them, according to the World Health Organization’s latest figures.

The virus can fell its victims within days, causing rampant fever, severe muscle pain, vomiting, diarrhoea and — in many cases — unstoppable internal and external bleeding.

In Sierra Leone, Ebola has infected 1,940 people, killing 593, by the WHO count, but the UN agency has warned the number of cases across the region could explode in the coming months without an urgent response.

– ‘Horrific suffering’ –

World leaders were due to attend a meeting in New York on Ebola convened by United Nations Secretary-General Ban Ki-moon later Thursday, with Koroma and Liberia’s President Ellen Johnson Sirleaf connected by video link.

The meeting — part of the United Nations General Assembly — will hear from US President Barack Obama and world leaders are expected to pledge help for efforts to try to contain the spread of the virus.

Obama, who is sending 3,000 troops to west Africa to aid local health workers battle the contagion, urged other countries Wednesday to get behind a broader international effort.

In a speech to the General Assembly, Obama grouped Ebola with the crisis in Ukraine and the threat posed by Islamic State group jihadists in Iraq and Syria as “new dangers” that imperil global security.