(New throughout, updates prices, adds comments; changes byline, dateline, previously SYDNEY)
CHICAGO, March 12 (Reuters) - U.S. wheat and corn futures weakened in technical selling on Monday while soybeans turned up on a bargain-buying bounce following an earlier three-week low, traders said.
Abundant global supplies and tepid demand for U.S. wheat continued to anchor prices, with benchmark Chicago Board of Trade May wheat down 4-1/4 cents at $4.85 per bushel, a 1-1/2-week low.
The U.S. Department of Agriculture said 389,358 tonnes of U.S. wheat were exported last week, within the range of expectations. Exports of 910,237 tonnes of soybeans also were within expectations while corn exports of 1.4 million tonnes topped estimates.
"U.S. wheat is flat-out uncompetitive, so people don't want to get long the Chicago market," Futures International analyst Terry Reilly said of CBOT wheat.
USDA later on Monday is due to release weekly crop condition reports for winter wheat states Kansas, Oklahoma and Texas - data that should show low wheat crop ratings amid drought in the Southern Plains.
In Argentina, light rains fell over the weekend and more widespread showers were possible later this week in parts of the No. 3 global soy and corn exporter. But the precipitation would not reverse damage on some plants after months of dry weather, agriculture meteorologists and analysts said.
CBOT May soybeans were up 2 cents at $10.41-1/4 per bushel, recovering from a session low of $10.32.
CBOT May corn edged 3/4 cent lower to $3.89-3/4 per bushel as of 11:15 a.m. CDT (1615 GMT).
Soybeans have weakened in recent days, pressured in part by fears of a fall in Chinese demand for North American supplies as trade war threats escalated.
"The threat of China retaliating after higher U.S. tariffs via soybeans has became more vivid," said Tobin Gorey, director of agricultural strategy, Commonwealth Bank of Australia.
Chinese officials have said U.S. soybeans are a prime target for retaliation against tariffs imposed by the Trump administration on steel and aluminum imports, the American Soybean Association said.
(Additional reporting by Colin Packham in Sydney and Sybille de La Hamaide in Paris Editing by Matthew Lewis)