U.S. wheat and corn futures rose by their daily trading limits on Thursday, while soybeans reached the highest level since 2012, after Russian forces attacked Ukraine, exacerbating worries over global supplies. Wheat rose for a third day, scaling its highest in more than nine years, while corn climbed to an eight-month peak.

Russian forces invaded Ukraine by land, air and sea, confirming the worst fears of the West with the biggest attack by one state on another in Europe since World War Two. With Russia and Ukraine accounting for about 29% of global wheat exports, 19% of world corn supplies and 80% of world sunflower oil exports, traders are worried conflict could hamper crop movement and trigger a mass scramble by importers to replace supplies from the Black Sea region.

"The surge in prices mirrors fears of a total halt in exports out of the Black Sea," Andree Defois, president of French consultancy Strategie Grains, said. "The problem is that importing countries still have (wheat) needs, we are not at the end of the campaign yet. If you see two or three million tonnes shifting to other origins, it is very bullish."

The most active May wheat contract on the Chicago Board of Trade soared 5.7% to $9.34-3/4 a bushel, the highest since July 2012. Corn climbed by up to 5.1% to $7.16-1/4 a bushel, its loftiest since June 10. May soybeans were up 2.8% at $17.18 a bushel at 1311 GMT, advancing for a sixth session.

Earlier in the day, the contract hit its highest since September 2012 at $17.56-1/2. In Paris, the most active May wheat contract was up 11% at 326.25 euros ($364.16) a tonne after reaching an all-time high for a Euronext contract at 341.75 euros per tonne shortly after the open.

Russia has suspended movement of commercial vessels in the Azov sea until further notice but kept its ports in the Black Sea open for navigation, its officials and five grain industry sources said. Egypt's state grains buyer GASC canceled its wheat import tender on Thursday. It had received only one offer.

"At the end of the day it will be importers who will pay the bill," Michel Portier, director general of Agritel consultancy, said. In China, soymeal futures on the Dalian Commodity Exchange rallied to a record high even as the government plans to release soybeans from reserves amid worries over tight supplies in the market.