Russian defence ministry says four boats carrying up to 50 Ukrainian special forces members were hit in aircraft attack.

An aircraft “destroyed four high-speed military boats” around midnight Moscow time [21:00 GMT], the Russian defence ministry wrote on the Telegram messaging app on Wednesday morning.

The boats were carrying “landing groups of Ukrainian special operations forces with a total number of up to 50 people,” the ministry said, without providing details as to where in the Black Sea the incident took place.

Early on Wednesday, Russian defences also repelled a “seaborne drone attack near” near Sevastopol Bay in Russian-annexed Crimea, the local Moscow-installed Governor Mikhail Razvozhayev was cited as saying by the state TASS news agency.

“Anti-submarine… forces have completed their work,” Razvozhayev said, without giving details.

Sevastopol is the base of Russia’s Black Sea fleet. The Russian reports could not be independently verified.

Both Ukraine and Russia have ramped up military activities in the Black Sea after a United Nations-brokered deal to ensure safe navigation for grain ships collapsed last month.

In recent weeks, Kyiv has attacked Russian ships in its waters and raided the Crimean Peninsula, which was annexed by Moscow in 2014, using military speedboats. Ukraine said its forces last week had raised the country’s flag in Crimea during a “special operation” to mark Ukrainian Independence Day.

Moscow also claimed last week that one of its jets destroyed a Ukrainian “reconnaissance boat” near Russian gas production facilities in the Black Sea, and a United States-made speedboat carrying Ukrainian soldiers east of Snake Island, without providing further detail.