Russia has launched an air attack on one of Ukraine’s major grain exporting ports, Ukrainian officials say, hours before Russian President Vladimir Putin and his Turkish counterpart, Tayyip Erdogan, were due to hold talks.

Ukraine’s air force urged residents of Izmail port, one of Ukraine’s two major grain-exporting ports on the Danube River in the Odesa region, to seek shelter after midnight on Monday. Some Ukrainian media reported the sound of blasts in the area.

Putin and Erdogan were to meet on Monday in the Russian Black Sea resort of Sochi as Ankara and the United Nations seek to revive a Ukraine grain export deal that helped ease a global food crisis. Ankara called the talks vital for the deal.

Russia quit the deal in July – a year after it was brokered by the UN and Turkey – complaining that its own food and fertiliser exports faced obstacles and that not enough Ukrainian grain was going to countries in need.

After quitting the Black Sea grain deal, Moscow has launched frequent attacks on the ports of the Danube River, which has since become Ukraine’s major route for exporting grain.

Monday’s attack – the scale of which was not immediately known – followed Russia’s strikes on Sunday on the other major Danube port of Reni, in which the port’s infrastructure was damaged and at least two people injured.