SINGAPORE, June 27 (Reuters) - Chicago corn futures edged higher on Tuesday after a U.S. government report showed crop ratings across the Midwest deteriorated to the worst in decades, raising concerns over global supplies.

Wheat and soybean futures slid in early Asian trade.

FUNDAMENTALS

* The most-active corn contract on the Chicago Board of Trade (CBOT) added 0.4% to $5.90-1/2 a bushel, as of 0015 GMT. Wheat lost 0.2% to $7.36-3/4 a bushel and soybeans fell 0.4% to $13.18 a bushel.

* The condition of U.S. corn and soybean crops deteriorated to the worst in decades, U.S. government data showed on Monday, as major producing areas missed out on much-needed rains.

* The weekly crop progress report from the U.S. Department of Agriculture (USDA) showed that good-to-excellent ratings for corn stood at 50% as of June 25, below the average of 11 estimates given by analysts in a Reuters poll that had predicted 52%.

* Just 51% of soybeans were in good-to-excellent condition, in line with analyst expectations. The ratings for both corn and soybeans were the lowest for this time of the year since 1988, the year of a historic crop-wasting drought.

* In the wheat market, focus is on supplies from the Black Sea region after concerns about political stability in major exporter Russia lifted prices to multi-month highs on Monday.

* An end to the Black Sea grains deal would hit the Horn of Africa hard, aid officials said on Monday, warning that another hike in food prices would add to the tens of millions of people facing hunger.

* Moscow has been threatening to walk away from the deal known as the Black Sea grain initiative - brokered by the United Nations and Turkey in July last year - if obstacles to its own grain and fertilizer shipments are not removed. A Ukrainian envoy has said he was 99.9% certain Russia would quit when it comes up for renewal on July 18.

* Ukraine's grain exports for the 2022/23 July-June season stood at 48.4 million tonnes as of June 26, four days before the end of the marketing year, agriculture ministry data showed on Monday.

* Russian wheat export prices rose for the second week in a row last week along with global markets, while the pace of exports also accelerated, analysts said.

* Commodity funds were net buyers of CBOT corn, soybean, soymeal and soyoil futures contracts on Monday, and net sellers of wheat, traders said.

MARKET NEWS

* Wall Street lost ground on Monday and crude prices advanced as investors digested the aborted Russian mutiny over the weekend and wrestled with lingering concerns over the path of Federal Reserve monetary policy.

DATA/EVENTS (GMT) 1000 France Unemp Class-A SA May 1230 US Durable Goods May 1400 US Consumer Confidence June 1400 US New Home Sales-Units May (Reporting by Naveen Thukral; Editing by Rashmi Aich)