Six people were killed and 39 injured in the overnight strike in the town of Starobilsk, in the Luhansk region, the Russian President said. Another 15 people were missing.

Ukraine's military said it had hit the headquarters of Russia's elite Rubicon drone military unit in Starobilsk. It did not say whether it was the same building as the one identified by Russia. But Putin said there were "no military facilities, intelligence service facilities or related services in the vicinity. Therefore, there is absolutely no basis for claiming that the munitions struck the building as a result of our air defence or electronic warfare systems", he said at a reception in his Kremlin residence in Moscow on Friday. He ordered the Russian military to prepare "proposals" on how to retaliate.

The Russian leader said the Ukrainian strike had been carried out in three waves using 16 drones. Russia's state-run TV showed what it said was one of the injured students, identifying her as Diana Shovkun, aged 19. She had head injuries after being hit by a collapsing concrete slab, the report said. No photos or videos of those who Moscow says were killed were shown.

On Saturday, Russian officials reported two people had been injured after falling debris from drones triggered a fire at an oil depot in Russia's Black Sea port of Novorossiysk. The general headquarters of the southern Krasnodar region said "several technical administrative buildings caught fire" and fragments of drones fell on a fuel terminal. Two people were injured and were being treated in hospital, the headquarters said. No deaths were reported. The general headquarters said drones had also damaged private homes in the port city of Anapa further north.

Ukraine's military said  on Friday that an overnight strike had targeted Rubicon's headquarters in Starobilsk. It accused fighters from the special drone unit of regularly striking civilians and civilian infrastructure in Ukraine. The statement also said that Ukrainian forces were "causing damage to military infrastructure and facilities used for military purposes, strictly adhering to the norms of international humanitarian law, laws and customs of war".

On Thursday, Ukrainian President Volodymyr Zelensky said the headquarters of Russia's security service FSB had been hit in the Moscow-seized area of Ukraine's southern Kherson region. About 100 Russian "occupiers" were either killed or injured, he added. Moscow's military has not commented on the issue, but one pro-Kremlin Telegram channel reported "casualties" after what it described as a "massive drone strike". Ukraine has repeatedly accused Russia's military of deliberately targeting civilians since the start of Moscow's full-scale invasion in 2022 - a charge Moscow regularly denies. (BBC)