* Weekly corn export sales below range of trade estimates
* Soybean sales near low end of estimate range
* Favorable Brazilian crop weather weighs on prices (Rewrites throughout with U.S. market activity, adds quote, updates prices, adds byline, changes dateline from PARIS)
CHICAGO, Nov 16 (Reuters) - U.S. corn futures fell to new contract lows for the third straight day on Thursday as lower-than-expected weekly export sales and abundant supplies weighed on the market.
Soybeans also declined on disappointing weekly U.S. Department of Agriculture export sales data and as improving crop weather in Brazil raised prospects that the world's top soy exporter would produce another bumper crop.
Export sales of both commodities this season are lagging the pace needed to reach the latest full-year export forecasts, partly due to stiff competition from South American shipments.
"The export sales were a bit of a disappointment and the fact that we didn't have any private sales announced is also hanging over this market," said Brian Hoops, president of Midwest Market Solutions.
The USDA said net U.S. old-crop corn export sales last week fell to 949,500 tonnes, below trade expectations for at least 1.2 million tonnes.
Net old-crop soybean sales of 1.1 million tonnes were at the low end of a range of trade estimates.
Widespread rains across northern and southern Brazil over the next two weeks is expected to boost recently planted crops there, forecasters said. Some areas of Argentina's crop belt are also expected to receive rains following early season dryness that have delayed planting, they said.
"Favorable weather (is) on the way for much of Brazil with the notable exception of the Northeast," Thomson Reuters Agriculture Research analysts said in a note, adding that soy and corn planting were progressing at a near average pace.
Chicago Board of Trade December corn fell 1-1/4 cents to $3.37 a bushel by 11:45 a.m. CST (1745 GMT) after posting a contract low of $3.36-1/4. It was the lowest price for a spot contract in two months.
CBOT January soybean futures shed 4-1/4 cents to $9.72 a bushel and were on pace to decline for the third time in four days.
Wheat futures edged higher in a modest rebound from Wednesday's technically driven slide and on expectations for reduced plantings in Europe.
Egypt's state grain buyer GASC bought 240,000 tonnes of Russian wheat in a snap tender that attracted fewer offers than normal and no U.S. wheat offers.
CBOT December soft red winter wheat futures rose 3-1/2 cents to $4.23-1/2 a bushel dropping 1.9 percent on Wednesday. Hard red winter wheat and spring wheat futures also advanced.
(Additional reporting by Naveen Thukral in Singaport and Gus Trompiz in Paris; Editing by Susan Thomas)