* Wheat falls after 2-day rise; soybeans, corn also pull back

* U.N. chief set to disclose talks on Ukraine grain exports

May 18 (Reuters) - U.S. grains futures fell on Wednesday following a report about the United Nation's efforts to restore Ukraine grain shipments that have been hampered by the war, and as worries about high prices curbing demand weighed on sentiment.

U.N. chief Antonio Guterres is expected to publicly disclose on Wednesday that he is in talks with Russia, Ukraine, Turkey, the United States and the European Union aimed at restoring Ukraine grain shipments and reviving fertilizer exports from Russia and Belarus, U.N. officials said.

Guterres has warned that the war in Ukraine, which has led to tighter global grains supply and fuelled a surge in prices, will worsen food, energy and economic crises in poor countries.

The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 2% at $12.51-3/4 a bushel, as of 0728 GMT.

CBOT wheat had climbed more than 8% over the past two days after India unexpectedly banned exports of the grain and following a U.S. Department of Agriculture report late Monday indicating worsening condition of the U.S. winter crop.

CBOT soybeans dropped 0.2% to $16.75-1/2 a bushel, after a six-session advance.

CBOT corn shed 0.3% to $7.98-1/4 a bushel, retreating after touching a two-week high on Monday.

"It appears that tighter supply and higher prices will weigh on global demand," said Warren Patterson, head of commodities strategy at ING.

For wheat, he said major supply losses are expected from Ukraine, while production from Argentina, Australia and the EU is also expected to decline next season which should offset supply gains from Russia and Canada.

Worries about the drought in the United States also remain

Crop scouts on the first day of an annual three-day tour of Kansas projected an average yield for hard red winter wheat in the northern portion of the drought-hit state at 39.5 bushels per acre, down from 59.2 bushels in 2021. (Reporting by Enrico Dela Cruz in Manila; Editing by Rashmi Aich and Louise Heavens)