By Chris Arsenault

ROME, Dec 17 (Thomson Reuters Foundation) - Half a million people in three West African nations rocked by Ebola are going hungry and that number could double by March if food supplies do not improve, two United Nations agencies warned on Wednesday.

In Guinea, Liberia and Sierra Leone, the countries at the heart of the worst recorded outbreak of Ebola, workers have been staying away from markets and fields for fear of spreading the virus that has killed more than 6,800 people since March.

This fear has caused labour shortages on farms for planting and weeding and cut household incomes, compounding an economic slowdown in these three countries.

Border closures and quarantines are disrupting supply chains, hindering market access and exacerbating shortages, raising fears that one million people from a combined population of 20 million could be going hungry by March.

"The outbreak has revealed the vulnerability of current food production systems and value chains in the worst Ebola-affected countries," Bukar Tijani, the Food and Agriculture Organisation's (FAO) representative for Africa said in a statement.

The FAO said more food needs to be imported into these countries which are facing a financial crunch because exports have dropped and recommended cash transfers or vouchers for affected people to buy food and help stimulate markets.

Denise Brown, a relief coordinator for the World Food Programme, said the situation regarding food supplies could get worse before improvements are seen from international efforts.

In Guinea, 230,000 people are estimated to be facing sever food shortages because of the impact of Ebola. By March 2015, the number is expected to rise to more than 470,000.

Nearly 300,000 Liberians are expected to face severe food problems by March, up from 170,000 today.

The drop in absolute food production across the three states in 2014 compared to the previous year has been relatively modest with an 8 percent drop in Liberia, 3 percent in Guinea and 5 percent fall in Sierra Leone.

The World Food Programme has provided aid to more than two million people in these three countries and UN agencies have asked for more funding from donors for 2015. (Reporting By Chris Arsenault, Editing by Belinda Goldsmith)