A Russian drone strike has hit port facilities in the south of Ukraine's Odesa region, starting fires, authorities say, Paralel.Az reports citing BBC.

A grain silo and port infrastructure were damaged, authorities said, without revealing which port was hit.

Ukraine's air force said earlier that drones were heading for the Danube river, where Ukraine has ports along the border with Nato country Romania.

Romanian media said the port of Izmail had been hit.

The Ukrainian port sustained serious damage, a source told Reuters news agency.

Russia began targeting Ukraine's ports after abandoning a UN grain deal. The agreement, brokered a year ago, had meant that Ukrainian and Russian exports could be shipped safely across the Black Sea.

Odesa regional leader Oleh Kiper said emergencies services were working on the site of the latest Russian attack, and there were no reports of any casualties.

He added that further information would be given by the Ukrainian military, and posted several images on social media indicating the scale of the damage.

Ukraine's military command in the south said air defences had been operating for almost three hours. President Volodymyr Zelensky said that "unfortunately there has been damage", most significantly in southern Ukraine.

After withdrawing from the grain deal, Russia threatened to target any vessels heading towards Ukraine's Black Sea ports - de facto imposing a naval blockade.

The Danube route has grown in importance as an alternative, via the Ukrainian ports of Izmail and Reni.

Last month, Russia destroyed grain storage infrastructure in Reni, across the Danube from Romania.

Ukraine is one of the major exporters of wheat and corn, and the bulk of the shipments had been moving from the country's Black Sea ports.

Wheat prices spiked on world markets immediately after the Russian withdrawal from the grain deal.

There are now also concerns about global food security, especially for impoverished African and Asian nations.

Overnight, Russia also launched more than 10 drones against Ukraine's capital Kyiv, local officials say.

All the projectiles were destroyed by anti-aircraft systems but several non-residential buildings were damaged by falling debris, the officials say.

Russia has so far not publicly commented on the reported attacks.