PARIS (AFP) - Border closures, quarantines and crop losses in West African nations battling the Ebola virus could lead to as many as one million people going hungry, UN food agencies said on Wednesday.

The deadly haemorrhagic fever that has killed 6,800 people has severely disrupted daily life in the worst-hit nations of Liberia, Guinea and Sierra Leone, the latter two of which have gone so far as to ban Christmas celebrations.

The UN Food and Agriculture Organisation and the World Food Programme said the disease and the resulting restrictions had "caused a significant shock to the food and agriculture sectors in the affected countries".

"The loss of productivity and household income due to Ebola-related deaths and illness as well as people staying away from work, for fear of contagion, is compounding an economic slowdown in the three countries," the agencies said in a joint statement.

Restrictions put in place to curb the disease were also "seriously hindering people's access to food, threatening their livelihoods, disrupting food markets and processing chains, and exacerbating shortages stemming from crop losses".

Half a million people are currently in severe danger of going hungry, but this could "top one million by March 2015 unless access to food is drastically improved and measures are put in place to safeguard crop and livestock production".

Labour shortages have interrupted planting and weeding of crops, while fear of contagion is keeping people away from markets.

"The outbreak of Ebola in West Africa has been a wake-up call for the world," said WFP Emergency Response Coordinator Denise Brown in Dakar.

"The virus is having a terrible impact on the three worst-hit countries and will continue to affect many people's access to food for the foreseeable future. While working with partners to make things better, we must be prepared for them to get worse," she said.