By Pavel Polityuk

KYIV (Reuters) -Russian drones struck Ukrainian grain facilities at the Danube River port of Izmail overnight in what a senior official said on Wednesday was a systematic attempt by Moscow to prevent Kyiv exporting grain to the world.

Deputy Prime Minister Oleksandr Kubrakov said the port's export capacity had been reduced by 15% and that 13,000 metric tons of grain had been destroyed.

Grain facilities in the Odesa region on the Black Sea also came under fire in the eighth wave of attacks on Ukrainian port infrastructure since Russia quit a U.N.-brokered deal last month that had allowed Kyiv to ship its grain via the Black Sea.

The Danube River has become Ukraine's main route for exporting grain since the collapse of the deal, which was meant to help tackle a global food crisis, and Izmail is Ukraine's main inland port across the Danube from Romania.

"13,000 tonnes of grain were destroyed by Russia as a result of the Shahed (drone) attack on the port of Izmail," Kubrakov said on the Telegram messaging app. "Several private grain terminals and warehouses were damaged, as well as cargo infrastructure."

He said the grain that was destroyed had been destined for Egypt and Romania, and that a total of 270,000 tons of grain had now been destroyed in attacks since Russia quit the Black Sea grain deal.

"This night alone, the export capacity of the port of Izmail was reduced by 15%," Kubrakov said. "Russia is systematically hitting grain silos and warehouses to stop agricultural exports."

The Ukrainian military published photographs showing piles of grain under the burnt and wrecked shell of a storage facility.

Russia did not immediately comment on the attacks, but blames Ukraine and its Western allies for the collapse of the Black Sea grain deal.

SOME DRONES SHOT DOWN

Odesa governor Oleh Kiper said the attack on the Odesa region lasted three hours and that the Ukrainian air force had destroyed nine Russian drones.

"Unfortunately, there were hits to the production and transhipment complexes where a fire broke out... The damage includes grain storage facilities," Kiper said on Telegram.

Ukrainian air defences said later on Wednesday they had shot down 11 out of 20 drones launched by Russia overnight.

Ukraine's Danube ports accounted for around a quarter of Ukrainian grain exports before Russia pulled out of the deal to provide safe passage for the export of Ukrainian grain via the Black Sea in July.

Ukraine operates two major ports on the Danube - Izmail and Reni. Global grain prices rose earlier this month, when Russia attacked Izmail and Reni.

(Additional reporting by Anna Pruchnicka, Writing by Pavel Polityuk, Editing by Timothy Heritage)