ROME (Reuters) - Prices of corn, wheat and other grains can go much higher and current weather patterns are of concern, the United Nations food agency said on Wednesday after announcing a record high for its food price index in December. The FAOs food price index, which measures monthly price changes for a food basket composed of cereals, oilseeds, dairy, meat and sugar, averaged 215 points last month, up from 206 points in November. That level, fuelled by soaring sugar prices and strength in cereals and oilseeds, was the highest since records began in 1990, and topped the high of 213.5 in June 2008, during a food crisis which sparked riots in some countries. Food and Agriculture Organisations economist Abdolreza Abbassian told Reuters the FAO was concerned by the unpredictability of current weather activity. There is still room for prices to go up much higher, if for example the dry conditions in Argentina tend to become a drought, and if we start having problems with winterkill in the northern hemisphere for the wheat crops, he said. Winterkill occurs when cold attacks plants seeded, generally in the autumn, for harvesting the following year. Abbassian added that despite high prices, many factors that triggered sometimes deadly food riots in 2008, such as weak output in poor countries and a sudden surge in crude oil prices, were not currently present, reducing the risk of more turmoil. A mix of high oil and fuel prices, growing use of biofuels, bad weather and soaring futures markets pushed up prices of food in 2007/08, prompting violent protests in countries including Egypt, Cameroon and Haiti. Last September 13 people were killed in Mozambique in riots which followed a 30 percent bread price rise sparked by the leap in global wheat prices. Prices of grains surged in 2010, with wheat buoyed by a series of weather events including drought in Russia and its Black Sea neighbours. European wheat prices doubled, U.S. corn rose more than 50 percent while U.S. soybeans jumped 34 percent. Low stocks of grains such as corn mean that more weather-related damage to crops could be critical for markets. China in particular has a huge appetite for corn and is keen to secure adequate stocks of the grain. The fundamentals of the corn market are clearly the tightest ones, said Societe Generale analyst Emmanuel Jayet. Its the grain where stocks are already very low and where there are questions about a further drop to historically low levels, he said, adding that rising corn prices would have a spillover affect on other grains markets. Crude oil prices have also crept higher on a resurgence in global demand, which has raised concern of a double burden of high food and energy prices particularly for developing countries with import needs, Abbassian said. Thats when people have problems because of inflation. Fast-growth developing countries are more vulnerable, he said, mentioning India and China. But he did not see the oil price buoying grains and oilseeds markets to the extent it did in 2007/08, because it had not seen such a drastic and sudden surge and because the biofuels industry is no longer growing as rapidly. The FAOs Sugar Price Index soared to a record high of 398.4 points from 373.4 points in November, while its meat price index also hit a record of 142.2 from 141.5 the previous month.. The Cereals Price Index, which includes prices of main food staples such as wheat, rice and corn, rose to an average of 237.6 points in December, the highest level since August 2008 and up from 223.3 points in November. Its Oils Price Index also jumped to 263.0 points in December from 243.3 points in November.