* Wheat futures lose momentum after rallying overnight

* Soybean futures see spillover support from firm wheat prices

* Corn futures gain strength from high wheat-corn spread

CHICAGO, May 22 (Reuters) - Chicago Board of Trade wheat futures climbed to a 10-month peak on Wednesday as worries grew about deteriorating harvest prospects in top exporter Russia, before the market turned lower.

Concerns about declining global supplies sent the benchmark CBOT wheat contract soaring to a premium of $2.39-1/2 per bushel over corn futures this week, the largest since Oct. 10, 2022.

The wide spread is expected to boost demand for U.S. corn for livestock feed, analysts said. The spread narrowed on Wednesday as corn futures rose and wheat backpedaled.

"Wheat’s been the lead for sure, and it’s been dragging corn right along with it," said Jim Gerlach, president of A/C Trading.

The most-active CBOT wheat contract was last down 2 cents at $6.95-3/4 bushel by 11:50 a.m. CDT (1650 GMT). It earlier reached $7.16-3/4, its highest since July 28.

Traders kept their attention on Russia, where rains may provide relief from dryness in the next 11 to 15 days, according to an analyst note.

In Ukraine, crops have also faced dryness and frosts. A state weather forecaster said frosts had not significantly damaged crops. but traders are wary after consultants APK-Inform on Monday warned of yield losses.

In the U.S., faster-than-expected corn and soy planting progress curbed market gains. Windows of dry weather, interspersed with rain in the Midwest, are expected to provide time for planting, analysts said.

Rains have slowed progress in some places.

"Planting delays are something the market is taking note of," said Brian Basting, analyst at Advance Trading.

CBOT soybeans were up 11 cents at $12.47 a bushel and corn was 3-1/4 cents higher at $4.61-1/4 a bushel. (Reporting by Heather Schlitz in Chicago. Additional reporting by Gus Trompiz in Paris and Peter Hobson in Canberra; Editing by Mrigank Dhaniwala, Sherry Jacob-Phillips, Louise Heavens and Jonathan Oatis)