Ukraine says satellite pictures show the destruction of a Russian warehouse used to launch Iranian-made drones and to train cadets.
The photos - posted by Ukraine’s Navy - follow reports of a massive explosion near a Russian airfield in the southern region of Krasnodar.
Moscow has yet to comment on the reports, but did say it has shot down a number of drones in the region overnight on Friday.
Navy officials in Kyiv said a number of training instructors and cadets learning to operate the Iranian-made Shahed drones were killed by the attack, which they said happened on Friday night.
In a post to Telegram, Navy officials in Kyiv said the operation was planned and conducted in partnership with Ukrainian intelligence agencies.
The base sat on the Sea of Azov opposite the occupied Ukrainian city of Mariupol, data from Planet Labs - the US-based company who took the photos - showed.
"New satellite images confirm the destruction on the night of June 21 of the Shahed-136/Geran-2 storage and preparation facilities, training buildings, control and communication points of these UAVs located in the Krasnodar Territory," naval officials wrote in a post to Facebook.
The photos posted to social media appeared to show two large warehouses bisected by a road running north-south on 11 April. Subsequent photos taken on Saturday showed one of the warehouses completely destroyed, with the other having sustained significant damage.
Russia said on Friday that it had shot down 114 drones during a Ukrainian attack on oil refineries and military targets in the south of the country. Officials said that one person was killed by falling debris, but did not mention the attack on the drone base.
On Saturday Russian-installed officials in occupied Crimea said three people including two children were killed in a Ukrainian missile attack on a beach on the peninsula.
Mikhail Razvozhaev - who was installed by Moscow as the regional governor in 2020 - said almost 100 people were injured by missile fragments.
Russia’s defence ministry said five projectiles had been destroyed by air defences but debris from the interceptions fell on coastal areas. Officials said the missiles were US-made ATACMS - which are capable of striking deep into Russian-held territory.
Elsewhere, the governor of Russia’s Belgorod region said further Ukrainian drone attacks overnight on Sunday left one person dead and three more injured.
Vyacheslav Gladkov said one of the drones destroyed a car park in Graivoron - about six kilometres (3.7 miles) from the Ukrainian border.
Meanwhile, officials in Kyiv said two people were injured and scores of residential buildings were damaged in a Russian missile and drone attack on the Ukrainian capital on Saturday night.
Ruslan Kravchenko, head of the Kyiv regional administration, said the people were injured by falling debris. He noted that six tower blocks, 20 private homes and several shops were damaged in the attack.
Ukraine’s air force said it destroyed two of three missiles launched by Russia towards the Kyiv region.
During his nightly address from the capital, President Volodymyr Zelensky once again renewed his appeal to Western nations to supply new air defences to Ukraine, specifically calling for Us-made Patriot systems.
"Ukraine needs the necessary forces and means to destroy the carriers of these bombs, particularly Russian combat aviation wherever it is," he said.