CHICAGO - U.S. wheat futures rallied on Friday, supported by concerns the grain deal allowing for Russian and Ukraine exports from Black Sea ports could splinter amid escalations in the nearly year-long war between the two countries, traders said.

Corn and soybean futures also were strong, with corn following the gains in wheat and soybeans supported by concerns about drought leading to crop shortfalls in Argentina.

The 3.8% rise in the most-active Chicago Board of Trade soft red winter wheat futures contract, its biggest daily gain since Oct. 31, pushed prices to their highest on a continuous basis since Jan. 3.

"Wheat has been the leader linked to increased tension in Ukraine, which could slow the Ukrainian exports and the planting for the 2023 crop and it could also lead to increased sanctions against Russia," said Mark Polowy, senior account executive at Archer Financial Services.

CBOT March soft red winter wheat futures settled up 28-3/4 cents at $7.86 a bushel.

Ukraine's agriculture ministry has proposed increasing the minimal tonnage of ships which carry grain and vegetable oil from the country. Russia's ambassador to the United Nations said Moscow has not been able to export any grain as part of the Black Sea grain deal.

Traders said it was likely that some short-covering also supported wheat, but it was impossible to know the extent as the U.S. Commodity Futures Trading Commission has been unable to publish its weekly report on traders' positions due to a ransomware attack.

CBOT March soybean futures gained 23-1/4 cents to $15.42-1/2 a bushel and CBOT March corn futures were 9-3/4 cents higher at $6.80-1/2 a bushel.

Expectations of a record Brazil soybean crop tempered worries over Argentine losses but rains threatened to delay harvest and push seeding of the country's safrinha corn beyond the ideal time frame.

(Additional reporting by Gus Trompiz in Paris and Enrico Dela Cruz in Manila; Editing by Chris Reese and Andrea Ricci)