* Strong demand in US supports CBOT soybeans

* Traders monitor drought in exporter Brazil

* Weekly US soy, corn export sales meet estimates

CHICAGO, Oct 19 (Reuters) - Chicago Board of Trade soybean futures pared gains on Thursday after rising to a four-week high on strong demand for U.S. supplies and drought in rival exporter Brazil.

A rally to August highs in soymeal helped support soybeans, traders said. They kept an eye on the world's biggest soy supplier Brazil, which has increased sales to China this year following a record harvest in the Latin American country.

Now, a drought in Brazil has slowed soybean plantings and disrupted crop shipments on barges.

"The strong competition from Brazil has been a problem for soybeans, but the domestic crush demand for soybeans is solid and the export demand for meal is supportive," said Tomm Pfitzenmaier, analyst for Summit Commodity Brokerage.

The most-active CBOT soybean contract was up 1-1/2 cents at $13.12-1/2 a bushel by 11:25 a.m. CDT (1625 GMT) after hitting its highest price since Sept. 21 at $13.17-3/4 a bushel. December soymeal was $5.4 higher at $419.2 per ton and hit its highest price since Aug. 28 at $420.4 per ton.

Weekly U.S. soybean export sales of 1.4 million metric tons for 2023/2024 were up 92% from the prior four-week average and within analysts' estimates. Soymeal export sales of 434,700 metric tons for 2023-24 were also within expectations.

"Meal prices continue to be supported by strong export demand for U.S. meal, which is the consequence of the poor soybean crop in Argentina that has left the U.S. as the primary meal supplier in the world," Pfitzenmaier said.

For corn, weekly U.S. export sales of 881,300 metric tons for 2023-24 were down 15% from the prior four-week average but within analysts' estimates.

However, difficult logistics in Brazil could create a short-term window of opportunity for improvement in U.S. export demand, a broker said.

CBOT corn rose 2-1/4 cents to $4.94-1/4 a bushel, while wheat was up 2 cents $5.82-1/4 a bushel after reaching a three-week high at $5.89-3/4.

(Reporting by Tom Polansek in Chicago. Additional reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by Tasim Zahid, Subhranshu Sahu, Will Dunham and Sherry Jacob-Phillips)