Kubrakov, writing on Facebook, said the Danube ports' infrastructure had been "devastated".
"Ukrainian grain is indispensable for the world and cannot be replaced by any other country in the coming years," he wrote.
"The port of Izmail suffered the most damage, including the terminal and infrastructure of the Danube Shipping Company."
Russian state news agency RIA said the port and grain infrastructure hit was housing foreign mercenaries and military hardware.
Seaport authority head Yuriy Lytvyn said on Facebook that repair work had already begun and the port infrastructure continued to operate.
Persons:
Oleksandr Kubrakov, Volodymyr Zelenskiy, RIA, Oleh Kiper, Yuriy Lytvyn, Nina, PUTIN, Vladimir Putin, Tayyip Erdogan, West, Putin, Erdogan, Ukraine Bridget Brink, Russia's, Farhan Haq, Pavel Polityuk, Peter Graff, Hugh Lawson, Daniel Wallis, Michelle Nichols, Simon Cameron, Moore, Philippa Fletcher, Giles Elgood, Cynthia Osterman
Organizations:
NATO, Romania Kyiv, Ukraine's, Russia reimposed, Facebook, Danube Shipping Company, Reuters, REUTERS, United Nations, Kremlin, International, Court, TASS, U.S, Rih, Thomson
Locations:
Romania, Russia, Ukraine, Izmail, Africa, China, Israel, Moscow, NATO, Russian, Odesa, Turkey, Soviet, Tehran, Kerch, Crimea, Ports, Kharkiv, Kyiv, Kherson, Constanta