Official says Sevastopol drone attack 'most massive' since start of conflict, Russia blames UK, Ukraine

A drone attack Saturday on Sevastopol port in Moscow-annexed Crimea was the "most massive" on the peninsula since the Kremlin sent troops to Ukraine in February, a Moscow-backed official said.

"Today at night, the most massive attack by UAVs (unmanned aerial vehicles) and remote-controlled surface vehicles in the waters of the Sevastopol bay was undertaken" since Moscow launched its offensive, Sevastopol governor Mikhail Razgozhayev told Russian state media, of the port that is home to Russia's Black Sea Fleet.

The Russian army accused the UK of helping Ukraine plan a drone attack on its Black Sea Fleet in the Crimean port of Sevastopol, and said that one of its ships suffered "minor" damage.

"The preparation of this terrorist act and the training of the military personnel of the Ukrainian 73rd Special Center for Maritime Operations were carried out under the guidance of British specialists located in the city of Ochakiv in Ukraine's Mykolaiv region," Moscow's defence ministry said in a statement.

Russia also said that its ships that were targeted in the drone attack in Crimea's Sevastopol port were involved in a UN-brokered deal to allow the export of Ukrainian grain.

"It should be emphasised that the ships of the Black Sea Fleet that were attacked by terrorists are involved in ensuring the security of the 'grain corridor' as part of an international initiative to export agricultural products from Ukrainian ports," Moscow's defence ministry said in a statement.