SINGAPORE: Chicago wheat gained more ground on Tuesday, climbing to its highest in a week as expectations of lower U.S. supplies in the next season and doubts over the renewal of a Black Sea export deal underpinned prices.

Corn and soybeans eased amid forecasts of record U.S. production.

"The USDA (U.S. Department of Agriculture) issued winter wheat harvested area, and after breaking down the area by class, Hard Red Winter wheat abandonment could end at 38.3%, highest in our recorded history going back to 1983," said Terry Reilly, a senior analyst at Futures International.

The most-active wheat contract on the Chicago Board of Trade (CBOT) rose 0.1% to $6.61-3/4 a bushel, as of 0213 GMT, after hitting its highest since May 8 at $6.64-1/4 a bushel.

Corn fell 0.4% to $5.90-1/4 a bushel and soybeans gave up 0.2% to $13.98-1/2 a bushel.

Wheat prices have been rising on fears of tightening supplies after the USDA's first official forecast of U.S. 2023-24 all-wheat production, at 1.659 billion bushels, fell below most analysts' expectations.

The harvest of hard red winter wheat in the drought-stricken Plains would be the smallest since 1957.

The UN aid chief said on Monday efforts will continue in coming days to extend a deal allowing the safe Black Sea export of Ukraine grain, a pact Russia has threatened to quit on May 18 over obstacles to its grain and fertilizer exports.

Export prices for Russian wheat continued to decline last week amid low demand and weakening global markets, and stormy weather affected volumes.

Prices for Russian wheat with 12.5% protein content, delivered free on board (FOB) from the Black Sea in June, were $248 a tonne, down $6 from last week, the IKAR agriculture consultancy said.

Corn and soybeans are facing headwinds after the USDA on Friday projected hefty year-on-year increases in supplies due to forecasts for record U.S. harvests of both crops. However, crop prospects will depend on Midwest weather in the coming months.

After Monday's market close, the USDA said the U.S. corn crop was 65% planted and soybean planting was 49% complete, both slightly behind trade expectations but still ahead of their respective five-year averages.

Commodity funds were net buyers of CBOT wheat, corn, soybean and soyoil futures contracts on Monday and net sellers of soymeal contracts, traders said. (Reporting by Naveen Thukral; Editing by Subhranshu Sahu)