Russia has launched a new attack on an inland port that has become one of the main grain export routes out of Ukraine since the collapse of the Black Sea deal in July.

The southern port of Izmail on the Danube River, which acts as the border between Ukraine and Romania, was hit with drones that damaged port infrastructure and grain silos, according to Ukrainian officials.

The port was also attacked a week ago despite previously being considered safe owing to its close proximity to Nato member Romania.

That attack led to freight rates increasing and some shipowners avoiding the area in the southern part of the Odesa region.

Grain shipments via Danube barges had been expanding rapidly since the start of the war as an alternative export route despite low volumes carried by smaller vessels, said Black Sea agricultural market analyst Andrey Sizov.

Ukraine’s Danube river ports accounted for a quarter of grain exports before Russia pulled out of the Black Sea Grain Initiative (BSGI) on 17 July. Barges take the grain to Romania’s Black Sea port of Constanta for onward shipment.

Russia’s withdrawal from the BSGI and threats from Moscow against commercial ships approaching Ukraine hit the stuttering long-distance grain trade out of Ukraine’s major ports.

That left the Danube barges, road and rail freight, among the few alternatives to get grain exports out of Ukraine. Low water levels in the Danube further affected volumes.

Ukrainian officials posted pictures of the aftermath of Wednesday’s attack including damaged buildings and silos with grain spilling out.

“Ukrainian grain has the potential to feed millions of people worldwide,” the defence minister said in a tweet. “However, Russia chose the path of killing, starvation, and terrorism.”

Wheat prices jumped in the aftermath of the attack amid concerns about the impact on global supplies. Ukraine is one of the world’s largest food exporters.