GRAINS-Soybeans sag on fears of fading U.S. export prospects

* Wheat up as Russia-Ukraine tensions may threaten exports

* U.S. wheat sale to Egypt adds support

* Corn follows soybeans lower

(Recasts; updates prices, adds quotes, changes byline, changes dateline from previous SINGAPORE/PARIS) CHICAGO, Nov 26 (Reuters) - U.S. soybean futures fell more than 2 percent and neared a four-week low Monday on chart-based selling and worries about export prospects for U.S. supplies amid a trade war with China, traders said. Corn futures followed soybeans lower. But wheat futures rose on fears that Russian-Ukrainian tensions could inhibit grain exports out of the Black Sea As of 12:31 p.m. CST (1831 GMT), Chicago Board of Trade January soybean futures were down 22-1/2 cents at $8.58-1/2 per bushel after dipping to $8.57, the contract's lowest since Nov. 1. CBOT December corn was down 3-1/4 cents at $3.55-3/4 a bushel after hitting $3.55-1/4, its lowest since Sept. 28, while December wheat was up 7 cents at $5.06-3/4 a bushel. The soybean sell-off accelerated as the benchmark January contract fell below chart support at its 50-day moving average near $8.72. Soybeans were pressured by fears of a prolonged trade war between the United States and China, by far the world's largest soybean importer. China has been buying Brazilian soybeans during the conflict and may be able to continue avoiding U.S. soy, given expectations of an early harvest in South America. "The window for U.S. soy exports to China is pretty much closed," said Terry Reilly, senior analyst with Futures International. U.S. President Donald Trump and Chinese President Xi Jingping are expected to meet on the sidelines of a G20 summit in Argentina this week, and Washington is set to raise tariffs on $200 billion worth of Chinese imports to 25 percent from 10 percent in January if there is no agreement. "Traders are growing skeptical that we will see meaningful progress toward a trade deal with China when President Trump and President Xi have dinner on Friday," INTL FCStone chief commodities economist Arlan Suderman wrote in a client note. Wheat futures rose for a second session as news of a U.S. wheat sale to Egypt and geopolitical tension in the Black Sea region sparked a round of short-covering. "Tensions between Russia and Ukraine during the weekend could have an impact on the level of loadings from Mariupol port as facilities are currently subject to increased controls," French consultancy Agritel also said. Mariupol is a grain export hub on the Sea of Azov, an arm of the Black Sea. The area has been at the center of a crisis

between Russia and Ukraine, which began on Sunday after Moscow

stopped three Ukrainian ships from entering the Sea of Azov.

Egypt's state grain buyer last week said it bought 240,000 tonnes of wheat in a tender on Thursday, with half coming from the United States. And the U.S. Department of Agriculture on Monday confirmed a private sale of 120,000 tonnes of U.S. soft red winter wheat to Egypt.

CBOT prices as of 12:30 p.m. CST (1830 GMT):

Net Pct Volume

Last change change

CBOT wheat WZ8 506.75 7.00 1.4 29812 CBOT corn CZ8 355.75 -3.25 -0.9 226785 CBOT soybeans SF9 858.50 -22.50 -2.6 101366 CBOT soymeal SMZ8 301.50 -4.30 -1.4 42009 CBOT soyoil BOZ8 27.00 -0.65 -2.4 57223

NOTE: CBOT December wheat and corn and January soybeans shown in cents per bushel, December soymeal in dollars per short ton and December soyoil in cents per lb.

(Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Richard Pullin and Edmund Blair)