* Coronavirus spread beyond China stokes grain demand worry
* Nearly all corn contracts, most 2021 soybeans hit new lows (Rewrites throughout with U.S. market open, adds quote, updates prices, changes byline, changes dateline from SINGAPORE/PARIS)
CHICAGO, Feb 24 (Reuters) - U.S. grain and soy futures tumbled on Monday as fears over the rapid spread of the coronavirus outbreak beyond China dragged down broader markets and underpinned the dollar.
Technical selling further fuelled the drop, with corn and soybeans down nearly 2% and wheat down more than 3%. Corn futures notched life-of-contract lows in nearly all months while most 2021 soybean contracts hit new lows.
Fears mounted that the coronavirus outbreak in China will grow into a pandemic with disruptive and deadly consequences for countries around the world, after sharp rises in infections in South Korea, Italy and Iran and first cases found in Kuwait, Bahrain and Iraq.
The surge of infections outside mainland China triggered steep falls in Asian and European shares and Wall Street stock futures as investors fled to safe havens such as gold. Oil prices tumbled 5%.
"The market is worrying about global trade slowing down, economic growth slowing down. And the dollar is finding strength against other currencies in a flight to safety and that makes our commodities less competitive globally," said Don Roose, president of U.S. Commodities in West Des Moines, Iowa.
"We have too big of supplies and demand is on shaky ground. With the spread of coronavirus beyond China, confidence in demand sunk even more today," he said.
Chicago Board of Trade (CBOT) May soybean futures were down 17-1/4 cents at $8.81-3/4 a bushel by 11:45 a.m. CST (1745 GMT) after earlier hitting a low of $8.79-1/4, the contract's lowest since May 23.
CBOT May corn touched a contract low and was down 5-3/4 cents to $3.75 a bushel in a fourth straight session of declines.
CBOT May wheat fell 19 cents to a 10-week low of $5.33 a bushel after breaching technical chart support at its 100-day moving average.
The U.S. Department of Agriculture (USDA) at its annual Outlook Forum last week projected a sharp increase in U.S. corn supplies in the 2020/21 season but a tightening of soybean stocks to a four-year low.
Demand for soybeans, however, remains uncertain as China, the world's top importer of the oilseed, struggles with the coronavirus outbreak and lingering effects from a fatal swine disease that has decimated its hog herd.
Soybeans also remain under pressure from a projected record-large harvest in Brazil, the world's top soy exporter.
(Additional reporting by Naveen Thukral and Sybille de La Hamaide; Editing by Marguerita Choy)