Kernel said in a statement on the Warsaw stock exchange late on Wednesday that the air strikes were on Sept. 2, Sept. 3 and Sept. 6 -- part of a series of Russian attacks which it said had "severely disrupted river export logistics".

Russian drones inflicted damage to "multiple critical assets", including vegetable oil storage tanks, in the attack on Sept, 2, the company said.

The next day, grain flat storages were targeted, resulting in the complete destruction of two flat storages with a combined storage capacity of 5,000 metric tons, it said.

Kernel reported no significant damage from the attack on Sept. 6.

"These relentless airstrikes are severely disrupting the export of agricultural products from Ukraine," Kernel said.

Russia has stepped up attacks on Ukraine's grain export infrastructure on the Danube and on the Black Sea port hub of Odesa since July 17, when it quit the U.N.-brokered deal that had allowed safe exports of Ukrainian grain via the Black Sea.

One of Ukraine's biggest agricultural goods exporters, Kernel exported 92,000 tons of grain, 98,000 tons of sunflower oil and 67,000 tons of sunflower meal in August.

"Export volumes were undermined by the challenges the Company faces, such as the inability to export goods through Ukrainian Black Sea ports and the ongoing Russian attacks on Ukrainian Danube port infrastructure, which have severely disrupted river export logistics," it noted.

(Reporting by Pavel Polityuk, Editing by Timothy Heritage)