GRAINS-U.S. wheat dips to 4-week low on sluggish export demand

* Black Sea region dominates global wheat export market

* Market eyes USDA's monthly supply-demand report Thursday (Adds quote, updates prices)

LONDON, Oct 10 (Reuters) - Chicago wheat futures fell to a four-week low on Tuesday, with a lack of demand for U.S. shipments in an amply-supplied world market dragging on prices.

The Chicago Board of Trade's most-active wheat contract was down 0.3 percent at $4.34-1/2 a bushel by 1030 GMT, after hitting its lowest since Sept. 12 at $4.34.

"Globally there is lots of wheat, the U.S. has to compete with lower prices," said one Australia-based commodities analyst. "U.S. wheat prices rose in September and the market is giving up those gains."

U.S. wheat exports are facing stiff competition from the Black Sea region.

Wheat prices in Russia, which has been dominating the global export market with a record crop, rose last week amid strong demand from buyers including Egypt and Saudi Arabia.

Black Sea prices for Russian wheat with 12.5-percent protein content and October delivery were at $193 a tonne on a free-on-board basis at the end of last week, up $2 from a week earlier.

The market is focusing on the world No.1 wheat importer Egypt, which set a tender on Monday to buy an unspecified amount of wheat from global suppliers for shipment from Nov. 20-30.

"The plentiful global supply, and especially the big crops from the Black Sea region, are continuing to weigh on the price. Lower prices are necessary to compete with this supply, which is why the EU wheat price on the Euronext in Paris is also under pressure," Commerzbank said in market note.

December wheat futures in Paris were down 1.00 euro, or 0.6 percent, at 163.00 euros a tonne.

There was additional pressure on the wheat market from improving soil moisture in U.S. winter wheat regions, where planting is under way. Rains crossed the southern U.S. Plains last week and showers were forecast in the Midwest this week.

CBOT's most active soybean contract was up 0.3 percent at $9.69-3/4 a bushel.

The absence of regular rains in the Midwest and Southeast of Brazil will hamper soybean planting this week but moisture will return to states like Mato Grosso over the coming days, according to a forecast by Rural Clima on Monday.

Investors are reluctant to take on big new positions ahead of the USDA's monthly supply-demand reports on Thursday. Analysts surveyed by Reuters expect the government to raise its estimates of U.S. corn and soybean yields and production in those reports.

CBOT's most active corn contract was down 0.2 percent at $3.48-3/4 a bushel. (Additional reporting by Naveen Thukral; Editing by Joseph Radford and Mark Potter)