Merchant ships face increased risks of damage from drifting sea drones after Ukraine stepped up its attacks against Russian naval vessels.

Ukrainian military intelligence claimed on Wednesday that it had sunk a Russian landing ship in the Black Sea, the second such attack this month.

The Cesar Kunikov sank near Alupka on the southern edge of the Russian-occupied Crimean Peninsula, according to reports.

The site is considerably closer to shipping lanes than in previous attacks, according to security and intelligence specialist Ambrey Analytics.

The Cesar Kunikov was probably part of the fleet of naval vessels that protected merchant ships using Russian-controlled Crimean ports, Ambrey said.

The Ukrainian military released footage that suggests at least three drones were involved in the attack, Ambrey said.

And it warned that sea drones deflected by Russian electronic warfare systems have been washing up on the shores of the Black Sea.

“These pressure-triggered USVs [unmanned surface vehicles] are known to have a payload of up to 320 kg,” Ambrey said.

“It was assessed that if a merchant vessel were to strike a drifting USV, the physical damage would likely be substantial.”

Ukraine’s military intelligence said the Cesar Kunikov had been sunk using Magura V5 sea drones, which have a reported top speed of 42 knots (78 km/h).

‘Foiled attack on merchant ships’

The Kremlin declined to comment on the attack.

Naval drones were also used to attack the Russian guided missile warship Ivanovets off the coast of Crimea on 1 February, according to the Ukrainian authorities.

Russia’s defence ministry claimed on Saturday that it had foiled a drone attack on merchant ships in the southwestern Black Sea.

It said one drone was destroyed by artillery while the others were “jammed with electronic warfare”.