Paris - While grain silos in many Western countries may overflow this winter, tens of millions of people risk going without food as hunger is being used more than ever as a weapon of war.More than 50 million people living in 17 conflict-ridden countries are in "severe food insecurity", two UN agencies warned recently.The protracted conflicts in Yemen and Syria place those two nations at the top of the list established by the Food and Agriculture Organisation (FAO) and the World Food Programme (WFP).Humanitarian catastropheIn Yemen, 14 million people - over half the population - are now considered to be facing a food crisis or emergency.Meanwhile in Syria, 8.7 million people or 37% of the pre-conflict population, "need urgent food, nutrition and livelihoods assistance", in particular aid to farmers, said the agencies.The same goes for parts of northeastern Nigeria, which has borne the brunt of an insurgency by Boko Haram islamists since 2009 and where the aid group Doctors Without Borders estimates half a million people face a humanitarian catastrophe. Thousands of hungry people forced from their homes by fighting had to wait until the end of July to receive their first food aid.Meanwhile, most of the world's top wheat producers are enjoying bumper crops, pushing prices down on global commodity markets and benefiting countries like Egypt that are dependent upon imports.But for countries gripped by conflict, importing food is logistically difficult if not impossible and at prices out of the reach of most of the population which have lost their livelihoods.Maintaining local agricultural production, even traditional small-scale farms, often becomes critically important for reducing hunger while helping keep down the number of refugees, said the head of the FAO's emergency unit, Dominique Burgeon.Rural population"It is clear that agriculture plays an important role in the resilience of populations faced with the shock of war," he said in a telephone interview. In certain parts of Syria this year people who have been displaced from other regions are helping till the fields and take in the harvest.Even so, that hasn't saved the agricultural sector, on which four-fifths of the rural population depends, from collapse."In Syria, all the industrial chicken farms have been destroyed, which affects the poorest people as chicken was the most affordable source of protein," said Burgeon.The FAO estimates that only 1.9 million tons of wheat will be harvested this year in Syria, less than half of the 4 million tons it produced before the war.Nevertheless, it has had difficulties in persuading donor nations to reach into their pockets to fund purchases of seeds, fertilisers and tools for Syrian farmers.In June, Pope Francis condemned the fact it is often more difficult to deliver humanitarian aid than to obtain weapons."It makes no difference where arms come from; they circulate with brazen and virtually absolute freedom in many parts of the world," said the pontiff during a visit to the WFP's headquarters. "As a result, wars are fed...not people."But the farm aid needs to be adapted to weather conditions in target countries.Burgeon warned that despite the best of intentions certain non-governmental organisations risked doing harm by importing seeds not appropriate for the local climate, which would "set the country back years". Farmers in Syria are already finding it impossible to obtain seeds developed by local agronomists due to the war, which has forced the closure of the nation's seed bank.Syria has become the first nation to make a withdrawal at the world's seed bank buried in a mountain off the Svalbard islands in the Arctic Ocean to replace destroyed local seeds.