Shafaq News/ Ukraine's spy chief said naval drones were effective against Russia despite many being destroyed.

Kyrylo Budanov said the maritime attack drones had successfully paralyzed Russia's Black Sea fleet.

He revealed that one drone forced Russia's Admiral Essen warship into dock for months for repairs.

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Ukrainian intelligence chief Kyrylo Budanov said naval attack drones have been able to "paralyze" the Russian Black Sea Fleet, Radio Svoboda reported.

He said that despite 60-70% of the drones being destroyed by Russian forces, they were still a highly effective "deterrent" and had been able to stall the Russian fleet's activities.

While refusing to provide an exact figure, he told the outlet that Ukraine was using "a lot" of the drones, and while the Russians destroyed many, the 30% they missed gave them a big problem.

The spy chief added that Ukraine had " a lot" of maritime drones, now being manufactured at scale.

Budanov noted one occasion when a sea drone had been destroyed as it approached Russia's Admiral Essen frigate in Sevastopol Bay.

"It seemed unsuccessful. But the blast wave, because it was destroyed about 100 meters from the ship, and the charge was quite powerful, the wreckage completely damaged some of the ship's electronic equipment, antennas, certain systems, and the hydroacoustic system. And it took 3-and-a-half months to repair," Budanov said.

Ukraine proved the threat offered by its sea drones earlier this month when it attacked a major Russian naval base in the Black Sea.

During the attack, a drone carrying about 1,000 lbs of TNT also hit a Russian warship, leaving it tilting and low in the water.

"A big navy ship, [the] Olenogorsky Gornyak, was hit," a Ukrainian source told CNN. "As the result of the attack, the Russian ship has received serious damage and is not able to fulfill its duties."

Anton Gerashchenko, an advisor to the minister of internal affairs in Ukraine, shared a video of the reported attack. It appears to show a drone heading straight toward the ship and slamming into it, with the video ending as the drone reaches the vessel.

Last month, Ukraine unveiled its new sea drone for the first time.

The Ukrainian-designed drone is remotely controlled and can be used for reconnaissance and surveillance missions. It can hold hundreds of pounds of explosives and hit targets 500 miles away.

These are faster than anything else in the Black Sea," a developer told CNN.

"Russia's equipment is from the 20th Century, and ours is from the 21st," he added.