A "massive" Ukrainian drone and missile strike on Russia's port city of Novorossiysk has damaged grain export terminals and hit the last major Russian naval base on the Black Sea.

Three people, including an eight-year-old child, were killed and 24 people were injured in the Wednesday nighttime attack.

Ukraine's Volodymyr Zelensky confirmed Ukraine had launched rocket and underwater drones in a "unique operation" to strike the Russian naval base at Novorossiysk, although he did not mention grain terminals being hit.

"The occupying fleet and all the infrastructure that supports it will not be safe as long as Russian aggression continues," Zelensky said.

Most of Russia's Black Sea fleet is docked in Novorossiysk - one of the largest ports in Russia - after it was forced to vacate its former home base of Sevastopol, in the Russia-occupied Crimean peninsula, which was too exposed to Ukrainian attacks.

A major grain trading company confirmed to Russia's TASS news agency that its terminal had been hit, while another told Reuters and Russian outlet RBK the same.

The Russian agriculture ministry announced on Wednesday that it was working to redirect cargo flows to ports in the Baltic and Caspian Seas as well as land routes. It did not make any reference to Ukraine's attacks but said it was "taking into account current logistical constraints".

Repeated explosions reportedly rang out over Novorossiysk throughout the night as air defences shot down aerial objects.

An emergency situation was declared in the city on Wednesday, after the barrage of drones struck areas around the port and damaged pipelines, suspending water supply for the city.

Elsewhere in the region a man was killed by drone debris, Regional Governor Veniamin Kondratyev said. Several locations in the surrounding Krasnodar region were also struck by "several hundred drones" overnight, Kondratyev added, with dozens of buildings damaged, including homes.

For its part, Moscow launched aerial strikes which killed at least 11 civilians overnight between Tuesday and Wednesday. The majority were killed when Russia hit the city of Zaporizhzhia with ballistic missiles and glide bombs.

Russia launched its full-scale invasion of Ukraine in 2022.

After a period of relative calm in the Black Sea, over the course of this summer Kyiv and Moscow resumed striking one another's ports and shipping.

The last remaining sea route out of Ukraine has been badly affected by several deadly Russian strikes on cargo ships and the port of Odesa, through which Moscow seeks to put off foreign companies from trading with Ukraine. In July, the Ukrainian Agribusiness Club (UCAB) reported a 23% decrease in exports.

Meanwhile, Ukraine has grown increasingly adept at carrying out long-range strikes on Russian territory. Its recent attacks on vessels in the eastern Black Sea have disrupted Russia's grain shipments, too.

Russia is the world's largest wheat exporter - but according to a Moscow-based analytics company, exports for August could fall by more than half compared to the same month over the last five years due to the disruption in the Black and Azov seas.

On Wednesday, Russian Foreign Ministry spokeswoman Maria Zakharova accused Ukraine of carrying out strikes on Russian grain and agricultural infrastructure, resulting in a hike in global food prices and growing grain shortages.

But Zakharova also said that for its part Russia would continue striking "facilities that [Ukraine's armed forces] use on the Black Sea to destabilise the navigation situation" until "the full elimination of threats to security projected to the Sea of Azov and the Black Sea".

Concerns over how the war in Ukraine would affect global food supplies have been persistent since Moscow invaded in 2022.

Together, Russia and Ukraine account for a significant share of global grain trade, particularly for buyers in North Africa, the Middle East and parts of Asia.

The 2022 Black Sea Grain Initiative, under which Russia agreed to lift its blockade on Ukraine's agricultural exports, did not last after Moscow resumed attacks on vessels using the maritime corridors to Odesa the following year.