The UN has been forced to revise its 2009 figures that one billion people worldwide were hungry, saying the number was closer to 870 million. In its new annual report, the UN Food and Agricultural Organisation (FAO) blamed flawed methodology and poor data for the erroneous assessment. But the FAO head said that, while the revised figures indicated progress, the numbers were still unacceptable. He said that the goal of halving hunger by 2015 was "still within reach". The UN defines hunger as the consumption of fewer than 1,800 kilocalories a day - the minimum required to live a healthy and productive life. Speaking at a conference in Rome, the FAO's Graziano da Silva said the 2012 report on food insecurity showed results over the past two decades were "better than previously believed". "We have good news, we have made some progress in reducing hunger," he said. 'Considerable fear' The revised figures indicate the global number of chronically hungry people has actually declined by 128 million since 1990, falling from 980 million people to 868 million, with a majority living in developing countries. This means that 12.5% of the world's population, or one in eight people, remains undernourished. However, Mr Silva said "most of the progress was achieved before 2007-08". He said "twin-track action" based on economic growth and safety nets for the most vulnerable was needed to meet the Millennium Development Goal of halving hunger by 2015. The slowdown was partially due to the global recession, rising food prices, growing demand for bio-fuels and climate change. The new report revealed Africa was the only region where the number of hungry has grown - from 175 million to 239 million over the last two decades, with nearly 20 million added in the past four years alone. Three years ago, the FAO's announcement that one billion people - a sixth of the world population - were suffering undernourishment grabbed headlines around the world. The study was aimed at assessing the impact of high food prices coupled with the global downturn. But, as it turned out, the calculations were wrong because they were based on figures from non-UN sources. "There was considerable fear that the combination of lower incomes and higher prices was going to cause significant undernourishment," the FAO's assistant director-general Jomo Kwame Sundaram said. "No-one really knows for sure if at any particular period that one billion figure was actually reached or not. We are recalculating everything with new, improved data and what we believe to be an improved methodology."