CHICAGO -- U.S. grains rallied Thursday amid fund buying, with corn at 10-year highs on robust weekly export sales and a weak dollar lifting sales prospects.

Wheat futures posted the best gains at the Chicago Board of Trade, the world's largest grain exchange, on speculative buying tied to positioning at the end of the month.

Traders said corn futures rose on buying by index funds, and support from government weekly export sales data.

"Export sales are hanging in there around the 1 million tonne area, that's supportive," said grains analyst Shawn McCambridge of Prudential Financial.

"I think most of the support today is a combination of technical support and ideas that the funds are going to be able to keep this market higher into the end of the month."

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Funds have been bullish on corn due in part to expectations for demand from the ethanol sector to keep expanding amid the thirst for cheaper alternatives to crude oil.

Large speculators were net long in corn futures and options by 290,782 contracts as of Nov. 21, up 2,681 from the previous week, according to the Commodity Futures Trading Commission.

Ethanol production in the United States topped the 1 billion gallon annual production mark with 1.1 billion gallons in 1992, and that production is expected to rise to around 4.3 billion by end of 2006, according to a private report.

CBOT traders said the corn market also was supported by weekly export sales data. The U.S. Agriculture Department said sales last week totaled 1.08 million tonnes, beating trade estimates for 800,000 to 1 million tonnes.

Corn futures inexplicably suffered a brief down moment when prices fell after what traders speculated was an erroneous trade on the exchange's electronic platform.

"Someone had a fat finger error on the electronic system and sold 2,000 March corn (contracts) at $3.77 instead of $3.87 and crashed the market 10 minutes before the close before we bounced back," said a trader.

The drop in corn futures, while brief, helped pare losses in feeder cattle futures traded across town at the Chicago Mercantile Exchange on hopes of lower feeding costs.

"...Once the corn started to break and the (feeder cattle) market started to rally the locals covered and there was just nothing for sale," said Jim Clarkson, livestock analyst with A&A Trading Inc. "It went from 97.200 to 97.500 (cents a lb) and then 97.500 to 97.850 on nothing but air."

Traders said wheat futures rose sharply, supported by weekly export sales data, fund buying and lower-than-expected deliveries against the December contract.

"We had good export sales which gave us a little bit of a fundamental spin," McCambridge of Prudential Financial said.

USDA said export sales of wheat totaled 547,800 tonnes last week, above estimates for 300,000 to 450,000 tonnes.

First-day deliveries against the CBOT December totaled 1,872 contracts, well below trade estimates for up to 5,000.

Traders and analysts were expecting a much higher number of deliveries due to low prices in the cash markets.

CBOT December wheat futures rose 11-1/2 cents to $5.02 a bushel, while December corn rose 6-3/4 cents to $3.77. January soybeans rose 3-1/4 cents to $6.85-1/2.

Live cattle futures at the Chicago Mercantile Exchange were supported by concerns that an impending snow storm across the U.S. Plains could slow marketings.

"It (weather) is not that big a factor, but it did cause some strength here," a trader said.

CME December live cattle futures rose 0.500 cent to 85.700 cents a lb.

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