CHICAGO, Nov 30 (Reuters) - U.S. wheat futures fell about 3% on Monday on prospects that Russia, the world's top supplier of the food grain, may raise its export quota, analysts said, along with long liquidation and profit-taking at the end of the month.

Soybean and corn futures dipped as welcome rains fell on parts of crop areas in Brazil and Argentina,

As of 12:53 p.m. CST (1853 GMT), Chicago Board of Trade March wheat was down 19-1/2 cents at $5.86-1/2 per bushel. CBOT January soybeans were down 21-1/4 cents at $11.70-1/2 a bushel and March corn was down 8-3/4 cents at $4.25 a bushel.

Wheat fell after Russia's agriculture ministry said the country may increase the size of its grain export quota planned for Feb. 15 to June 30 to 17.5 million tonnes, from 15 million tonnes.

"It does make a little bit more (wheat) available to the world market," said Jack Scoville, vice president for Price Futures Group in Chicago.

Also, the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) raised its estimate of the country's 2020/21 wheat production to 31.17 million tonnes, up from 28.91 million previously.

CBOT soybean and corn futures retreated after early advances, pressured by weekend rains in dry areas of Argentina and southern Brazil.

"The worry about dry weather in South America, especially Brazil and Argentina, has been supporting soybeans in the past week and now we are seeing rain in parts of these countries," said Matt Ammermann, StoneX commodity risk manager.

CBOT most-active corn futures touched their highest level since July 2019 in early moves on Monday before turning lower. And the benchmark soybean contract turned down after failing for a fourth straight session to match its Nov. 23 high of $12 a bushel.

"When you are in a weather market and all of a sudden the weather changes, you are going to get a reaction," Scoville said. "Plus, there is some liquidation just because it is the end of the month, and some of the funds are booking some profits." (Reporting by Julie Ingwersen in Chicago Additional reporting by Michael Hogan in Hamburg and Naveen Thukral in Singapore Editing by Matthew Lewis)