U.S. corn futures are expected to start stronger Friday on a resurgence of foreign demand for the grain following a drop to six-week lows.

Traders predict corn for July delivery, the most actively traded contract, will start 5 cents to 10 cents a bushel higher at the Chicago Board of Trade. In overnight electronic trading, the contract rose 6 1/2 cents, or 1%, to $6.87 a bushel.

Leading prices higher is an announcement from the U.S. Department of Agriculture that private exporters struck deals to sell 271,200 metric tons of corn to "unknown destinations" for delivery during the 2011-2012 marketing year, which begins in September. The sale fueled talk that China had re-entered the global market with its massive buying power to take advantage of the drop in corn prices. The chatter first emerged after corn dropped its daily, exchange-imposed limit Wednesday when the U.S. Department of Agriculture said inventories wouldn't be as tight as previously expected. Still, there has been no confirmation of business with China.

"With it being unknown destinations for the new crop, I'm sure it'll be attributed to China, even though we can't confirm that one way or another," said Shawn McCambridge, senior grains analyst for Prudential Bache, a brokerage in Chicago.

Grain traders are keeping a close eye on demand after prices reached record highs last month on steady buying from foreign countries and domestic producers of livestock and ethanol. The increase in demand follows a recent slowdown in export sales attributed to the spike in prices. Corn has pulled back 12.5% from its all-time high.

South Korea has been an aggressive buyer following the drop in prices. The Busan branch of the Korea Feed Association purchased a cargo of 55,000 metric tons of corn, trading executives said Friday, bringing South Korea's total corn purchases in the last five days to at least 487,000 tons.

The business with South Korea is significant because South Korean buyers have been staying away from the market for the last few weeks and buying cheaper feed wheat instead. Their last major corn purchases were made almost two months ago, when prices fell following the earthquake in Japan.

"Exporter phones started ringing following the bearish reaction of the USDA report and have not stopped," said AgResource Company, a Chicago-based agricultural consultancy.

The aggressive buying may be linked to expectations that prices will soon rebound because weather woes have hit major grain exporting countries, including the U.S. and European Union members, analysts said.

An unusually cool, wet spring in the U.S. delayed early planting of the corn crop, raising concerns that next fall's harvest won't meet expectations. Traders remain nervous about the potential for more weather problems this spring and during the growing period this summer.

"If physical buyers make purchases on dipping prices, it is a strong sign that prices may rise again or else they would have put off their buying," Barclays Capital Vice President Sudakshina Unnikrishnan said.

The USDA will issue an update on planting progress in a weekly crop report Monday. Traders predict planting will be anywhere from 57% to 70% complete. As of Sunday, planting was 40% complete, below the average of 59% for that time of year.