GRAINS-Wheat at 3-week high on supply concerns
* Wheat up for third day as frost hurts Argentine crop
* Expectations of strong China demand support wheat
* Soy firm on U.S. crop uncertainty, corn rebounds from 6-week low
(Updates after European markets) PARIS/SINGAPORE, Sept 25 (Reuters) - The price of U.S. wheat rose for a third session on Wednesday to its highest in more than three weeks, as frost threatened crops in Argentina and on expectations of strong demand from China. Soybeans rose slightly as uncertainty over U.S. production underpinned prices while corn rebounded from six-week lows. Argentina's wheat belt was hit by frost early on Tuesday that threatened to damage 2013/14 crop yields, meteorologists said, warning more cold weather was on the way. "Unfavourable crop conditions in Argentina could reduce the global supply of wheat and overseas buyers will turn to U.S. wheat," said Joyce Liu, an investment analyst at Phillip Futures Singapore. "China needs to import more wheat to meet its needs as bad weather ruined its domestic crop." However, traders in Europe noted that the impact of frosts on final harvests remained uncertain as they came at a non-crucial time of crop growth. Chicago Board of Trade December wheat rose as much as 0.76 percent to $6.64 a bushel, the highest since September 3. December corn was up 0.45 percent at $4.50-3/4 a bushel, after hitting a six-week low of $4.48 a bushel on Tuesday. November soybeans gained 0.53 percent to $13.19-1/2 a bushel. Chinese wheat prices have hit record peaks due to dwindling high-quality supplies and growing expectations state purchase prices will rise before the planting season begins next month.
Beijing, keen to encourage farmers to grow more wheat for the 2014 harvest, is expected to announce an increase in the price it pays for grain for its national stockpiles before planting begins in October. In the soybean market reports of variable yields from the early harvest dragged on prices for the oilseed. With the U.S. soybean harvest under way - 3 percent of the crop had been cut by Sept. 22 - commodity analysts remain unsure about how many acres were planted last spring, making it difficult to determine the crop size of the world's largest producer. Satisfactory weather is expected over the next couple of weeks for harvesting of the 2013 U.S. corn and soybean crops, an agricultural meteorologist said. "Expectations of a record corn output will continue pressuring corn prices going forward," said Liu.
* Prices as of 1123 GMT
Product Last Change Pct
CBOT wheat 663.25 5.00 +0.76 CBOT corn 450.75 2.00 +0.45 CBOT soy 1320.25 7.75 +0.59 Paris wheat 189.25 1.75 +0.93 Paris maize 167.75 1.75 +1.05 Paris rape 362.75 0.25 +0.07 WTI crude oil 103.64 0.51 +0.49 Euro/dlr 1.35 +0.30
* CBOT futures prices are in cents per bushel, Paris futures in euros per tonne, WTI crude oil in dollars per barrel.
(Additional reporting by Valerie Parent; editing by James Jukwey)