* Frosts damage crops in key exporters Russia and Ukraine

* Brazil foods continue to support soybean prices

LONDON, May 20 (Reuters) - Chicago wheat prices rose on Monday, rebounding from losses late last week, with the market buoyed by concerns about crops in several key exporting countries including Russia and Ukraine.

Soybean futures were higher with crop losses in Brazil following rains and heavy flooding continuing to provide support while corn also firmed.

The most-active wheat contract on the Chicago Board of Trade (CBOT) added 2.8% to $6.69-3/4 a bushel by 1048 GMT, climbing back up towards last week's 10-month high of $6.97.

The 2024 harvest in Russia - the world's biggest exporter of wheat - suffered from a prolonged return of frost in May, which affected the central and part of the southern regions of the country. As of May 16, eight regions had introduced a state of emergency due to the destruction of crops.

Recent severe frosts

across Ukraine's northern and eastern regions could also lead to yield losses.

Soybeans rose 0.3% to $12.31-1/2 a bushel and corn gained 0.4% to $4.54-1/2 a bushel.

Crop harvesting in Brazil's flood-devastated Rio Grande do Sul advanced slowly in the last week after relentless rains and stubbornly high waters failed to subside.

Excessive rains and heavy flooding have continued to constrain cargo movement at Rio Grande port, which is the fourth largest in the country for soybean exports and third largest for fertilizer imports.

In the U.S., soybean plantings are around 46% complete and corn about 75% with some concern that rains in the U.S. Midwest may slow progress.

The Commodity Futures Trading Commission's commitments of traders report showed non-commercial traders, a category that includes hedge funds, trimmed their net short position in CBOT wheat and increased their net short position in soybeans. (Additional reporting by Naveen Thukral in Singapore; Editing by Sherry Jacob-Phillips, Sohini Goswami and Vijay Kishore)