* Weak CBOT soyoil pressures soybean futures

* China, unknown buyers purchase US soybeans

* Most-active KC wheat reaches July 2021 low

CHICAGO, Nov 24 (Reuters) - Chicago Board of Trade soybean futures tumbled on Friday under pressure from favorable rains in Brazil, the biggest global supplier, analysts said.

The market has pulled back about 5% since jumping last week to its highest price since August amid concerns over hot, dry weather reducing output in northern and central Brazil. The area of concern shrank this week, traders said.

"Brazil rains pick though early next week," said Terry Reilly, senior agricultural strategist for Marex.

CBOT soybeans fell 25-3/4 cents to close at $13.30-3/4 per bushel.

Agribusiness consultancies Safras & Mercado and hEDGEpoint lowered forecasts for Brazil's 2023/24 soybean output, though analysts still expect the country to produce a record crop.

In Argentina, a major soybean oil and meal exporter, the grains trade is largely "paralyzed" by a lack of soybeans, the main export chamber said. However, the first sprouts of the 2023/24 soybean crop appear in good shape after rains.

"Soil conditions are more favorable than they were earlier this season or in previous years," John Stewart and Associates said.

Losses in CBOT soyoil helped drag down soybeans, traders said, after a U.S. appeals court said on Wednesday it struck down the Biden administration's decision to deny small refiners "hardship waivers" that exempt them from biofuel mandates.

January soyoil sank 2.42 cents to end at 50.29 cents per lb.

CBOT corn fell 5-1/4 cents to $4.82-1/2 a bushel, while wheat slid 7-1/4 cents to $5.77-1/4 per bushel. Most-active K.C. wheat hit its lowest price since July 2021.

The U.S. Department of Agriculture reported exporters sold 129,000 tonnes of U.S. soybeans to China and another 323,400 tonnes of U.S. soybeans to unknown buyers.

The USDA separately said 2023/24 U.S. soybean export sales in the week ended Nov. 16 were 961,300 metric tons, toward the low end of analysts' estimates. Weekly U.S. corn export sales for 2023/24 were toward the high end of estimates, while wheat sales met expectations. (Reporting by Tom Polansek in Chicago; Editing by Richard Chang)