* Wheat futures down on expected bumper harvest in Russia

* Brazil's 2022/23 corn production estimate raised from April's

SINGAPORE, May 30 (Reuters) - Chicago wheat futures slid more than 1% on Tuesday with the market giving up previous session's gains as expectations of a bumper harvest in Russia, the world's biggest exporter of the grain, pressured prices.

Corn and soybeans edged lower.

The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 1.3% at $6.08 a bushel, as of 0455 GMT. Corn fell 0.3% to $6.02 a bushel and soybeans slid 1.1% to $13.22 a bushel.

Export prices of Russian wheat are softening further in anticipation of a new harvest and amid low demand from global importers, analysts said.

A deal to allow Ukraine to export its grain safely across the Black Sea had been extended two weeks ago for two months.

Russia, however, warned the West on Monday that the grain deal would cease unless a United Nations agreement aimed at overcoming obstacles to Russian grain and fertiliser exports was fulfilled.

In the corn market, plentiful supplies from Brazil weighed on prices. Brazil's total corn production in 2022/23 is expected to hit 127.4 million tonnes, agribusiness consultancy AgRural said on Monday, raising its April estimate of 125.1 million tonnes as growers start to harvest their second crop.

The U.S. Department of Agriculture is expected to issue a weekly update on corn and soybean planting progress and its first condition ratings of the season for the corn crop later in the day. The government has projected supplies of both crops will rise sharply in the coming year due to forecasts for record harvests.

For soybeans, if there are good rains in the forecast after June 8, there will be far less concern about crop conditions. according to a note from commodities research firm Hightower.

However, if the forecast stays dry then the trade will be nervous over stressful conditions. Demand factors have remained weak and there is no technical sign of a low, the report added.

Heavy rain has flooded wheat fields in China's central Henan province, just days ahead of the harvest, pushing up prices and raising concerns about the quality of this year's crop in the world's top consumer of the grain.

Large speculators increased their net short position in CBOT corn futures in the week ended May 23, regulatory data released on Friday showed.

The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, increased their net short position in CBOT wheat and switched to a net short position in soybeans. (Reporting by Matthew Chye and Naveen Thukral; Editing by Sherry Jacob-Phillips and Shailesh Kuber)