By Lin Taylor

LONDON (Thomson Reuters Foundation) - As Sierra Leone recovers from the deadly effects of Ebola, more than half the population face food shortages, and many will not cope if further disasters such as drought or floods strike, U.N. food agencies said on Thursday.

Food shortages in most of the West African are caused by problems that predate the Ebola outbreak, the World Food Programme (WFP) and Food and Agriculture Organization (FAO) said.

Some 3.5 million people do not have enough safe and nutritious food to eat, the agencies said in a report published on Thursday.

Of that number, around 600,000 people face severe food shortages and are not prepared for sudden shocks such as food price increases, floods or droughts.

The report said the number of people "severely" affected by a lack of food has increased by 60 percent since 2010.

The Ebola outbreak - now officially over - worsened food shortages in some districts, notably Kailahun and Kenema, but in most of the country the problem is chronic, the report said.

"The results confirm that drivers of food insecurity are low agricultural productivity, poverty and a lack of resilience," Nyabenyi Tipo, FAO representative in Sierra Leone, said in a statement.

Poor roads, the difficulties farmers face in reaching markets, gender inequality, and a lack of alternative means of generating an income, also play a part, Tipo added.

Most of the population relies on agriculture for their survival, the report said.

Rice production fell by 15 percent over the last five years, and only about four percent of farmers grow enough rice to meet their needs for the whole year, Tipo said.

On average, 99 percent of agricultural workers use manual tools and only ten percent have access to better seed varieties, the report said.

Ebola killed more than 11,300 people and infected some 28,600 as it swept through Sierra Leone, Liberia and Guinea from 2013 in the world's worst outbreak of the disease.

During the epidemic, many farmers were unable to grow or sell their crops because of travel restrictions, border closures and quarantines, as well as fear of infection.

Food production in Sierra Leone's bread basket and epicenter of the epidemic stalled, and weekly markets ceased trading because there was nothing to sell, according to the World Bank.

The World Health Organization declared Sierra Leone free of the deadly hemorrhagic fever on March 17, Guinea on June 1, and Liberia on June 9.

According to Thursday's report, the Sierra Leonean districts of Kailahun, Kambia, Port Loko, Pujehun, and Tonkolili have the highest levels of food insecurity.

By identifying vulnerable regions, agencies hope to improve food production and people's access to food, and help communities become more resilient to future crises, the WFP said.

(Reporting by Lin Taylor @linntayls, Editing by Alex Whiting; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters that covers humanitarian issues, conflicts, global land and property rights, modern slavery and human trafficking, women's rights, and climate change. Visit http://news.trust.org to see more stories)