GRAINS-U.S. soybeans, corn tumble as China slaps tariffs on crop imports

* China says tariffs on $50 bln U.S. goods include soybeans, corn

* Investors rattled as China targets huge soybean trade flows

* Soy, corn trim losses after trading pause (Updates prices, adds comments; changes byline, dateline, previously PARIS)

CHICAGO, April 4 (Reuters) - Chicago soybean futures tumbled 3 percent on Wednesday, headed for the biggest daily loss since August after China proposed tariffs against U.S. soy, corn, beef and other goods to retaliate against the Trump administration's tariffs on Chinese exports as a trade war intensified.

U.S. corn futures also fell sharply, then recovered a portion of the heavy losses as trading resumed following a midmorning pause. Wheat prices ticked narrowly lower, tracking soy and corn.

Soybeans for May delivery were off 31-3/4 cents at $10.06-3/4 per bushel at 10:02 a.m. CDT (1502 GMT). Earlier, soybeans had plunged 5 percent to a two-month low of $9.83-1/4.

China announced that it would impose tariffs on U.S. agricultural products, planes and chemicals in response to Washington's proposed duties on Chinese electronics and other exports.

Soybeans were seen as one of China's best weapons in a trade war and Beijing announced its tariffs 11 hours after the move by Washington.

"The big reaction is on soybeans because the trade impact is the greatest, with 35 million tonnes of U.S. soybeans imported a year by China," said Michel Portier, head of consultancy Agritel.

China cannot import the same volumes of soybeans without buying from the United States. Top exporter Brazil just reaped a bumper harvest but Argentina's soy crop was reduced sharply by drought, limiting potential alternative suppliers.

"Confirmation of the details are needed for a full assessment, but it seems there will be an import levy on U.S. soybeans," said Matt Ammermann, Commodity Risk Manager at INTL FCStone. "In the near term it looks bearish for prices as some investors are selling futures right now and will likely ask questions later."

China did not set a date on when it would impose the tariffs.

"This doesn't change the world supply and demand," said ED&F Man Capital Markets analyst Jeff Thompson.

The U.S. Department of Agriculture on Wednesday said China bought 129,000 tonnes of U.S. soybeans within the past 24 hours and 325,000 tonnes were sold to unknown destinations.

China is less dependent on imports of U.S. corn and wheat due to its longstanding national security pledge to be self sufficient in grains.

Chicago Board of Trade May corn futures were down 7 cents, or 1.9 percent, to $3.81-1/2, above an earlier low of $3.72. CBOT May wheat was 3/4 cents lower at $4.56-3/4. (Additional reporting by Gus Trompiz and Sybille de La Hamaide in Paris, Michael Hogan in Hamburg and Colin Packham in Sydney; Editing by David Gregorio)