U.S. grain, soy futures surge on Black Sea supply concerns

* Concern mounts over Black Sea region export disruption

* Egypt cancels wheat tender amid market turbulence

* China, unknown buyers purchase U.S. soybeans

CHICAGO, Feb 28 (Reuters) - U.S. wheat futures spiked on Monday after hitting 13-1/2-year highs on Friday, lifted by concerns that Russia's invasion of Ukraine and Western sanctions will continue to disrupt grain exports from the Black Sea region.

Corn and soybean futures also rallied on worries over the crisis.

Egypt's state grains buyer, the General Authority for Supply Commodities, cancelled a second international tender for wheat amid supply uncertainty and market turbulence following the invasion.

"The prospects of Black Sea grain flows halted for 1-3 months will attract new buying on breaks," Rich Feltes, head of market insights for broker RJ O'Brien, said in a note.

The Chicago Board of Trade's most active wheat contract was up 42 cents at $9.01-3/4 a bushel by 10:15 a.m. CST (1615 GMT), after reaching a session high of $9.34-3/4. On Friday, the contract touched $9.60-3/4, its highest since summer 2008.

Most-active corn futures climbed 28 cents to $6.83-3/4 a bushel, while soybeans were up 50-1/2 cents at $16.35 a bushel.

"There are fears the fighting will not be over quickly and that wheat, grain and oilseed export shipments from Ukraine will face disruption for a longer period than initially expected," a European trader said.

"The impact of sanctions on Russia is also being assessed. Importers will have to switch elsewhere at a time of pretty tight global supplies."

Traders said most Ukrainian and Russian Black Sea and Azov Sea ports remained closed on Monday, though Russia's large grain export port Novorossiysk was operational.

Russia and Ukraine account for about 29% of global wheat exports, 19% of world corn supplies and 80% of world sunflower oil exports.

In other news, exporters reported the sale of 136,000 tonnes of U.S. soybeans to China for delivery in the 2022/23 marketing year and 120,000 tonnes of U.S. soybeans for delivery to unknown destinations during 2021/22, the U.S. Department of Agriculture said. (Reporting by Tom Polansek in Chicago and Michael Hogan in Hamburg Additional reporting by Naveen Thukral in Singapore Editing by David Goodman and Tomasz Janowski)