Wheat nears four-week low on worries about export demand, ecomony

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Corn, soy futures set two-week lows

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Markets trade in "risk off" mode -analyst

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U.S. to issue weekly export sales data Friday

CHICAGO, Jan 5 (Reuters) - Chicago Board of Trade wheat futures fell to their lowest price in almost four weeks on Thursday, while corn and soy hit two-week lows under pressure from concerns about weakening demand for commodities, analysts said.

Wall Street's main indexes also fell on increasing fears of elevated interest rates for longer than expected. Concerns over economic headwinds, including the impact of a surge of COVID-19 cases in China, spilled over into the grain markets, analysts said.

"For this most part this is macro," said Ted Seifried, vice president and chief market strategist for Zaner Ag Hedge. "This is risk off. This is concerns about China and the Covid situation over there."

The most-active wheat contract on the Chicago Board of Trade fell 2-1/4 cents to $7.43-1/4 a bushel by 12:05 p.m. CST (1805 GMT). The contract earlier set its lowest price since Dec. 9 at $7.36 a bushel.

Most actively traded soybeans were down 17-1/2 cents at $14.66 a bushel after touching their lowest price since Dec. 22 at $14.65 a bushel. Corn slid 3-1/4 cents to $6.50-1/2 a bushel and hit its lowest price since Dec. 20 at $6.48-1/2.

"There's a lot of doubt about demand, not just for grains but global demand for commodities as a whole," Seifried said.

The U.S. Department of Agriculture on Friday is expected to report total weekly export sales were 200,000 tonnes to 675,000 tonnes for wheat; 400,000 tonnes to 1.2 million tonnes for corn; and 400,000 tonnes to 1.325 million tonnes for soybeans, analysts said.

For wheat, the availability of abundant low-priced supplies from Russia and Ukraine are giving stiff competition to other global exporters, traders said.

Russia's January wheat exports will remain high for this time of the July-June marketing season - near at least 3.6 million tonnes - after a huge 2022 grain crop, analysts said. (Reporting by Tom Polansek in Chicago. Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Uttaresh.V, Frances Kerry and David Evans)