Andriy Yermak, the Ukrainian President's chief of staff, posted a video on Telegram of three soldiers raising a large Ukrainian flag on the island, from which Russian forces withdrew on June 30.
Meanwhile, Russia's Defence Ministry said that a Russian warplane struck Ukraine's Snake Island in the Black Sea overnight, shortly after Ukrainian troops claimed to have raised their flag over the island.
Ukraine summons Turkish envoy after Russian grain ship's departure
Ukraine's Foreign Ministry said a Russian ship carrying Ukrainian grain had been allowed to leave the Turkish port of Karasu, calling it an "unacceptable situation" and summoning Turkey's ambassador.
"We regret that Russia's ship Zhibek Zholy, which was full of stolen Ukrainian grain, was allowed to leave Karasu port despite criminal evidence presented to the Turkish authorities," Foreign Ministry spokesperson Oleg Nikolenko wrote on Twitter.
"Türkiye's Ambassador in Kyiv will be invited to Ukraine's Ministry of Foreign Affairs to clarify this unacceptable situation," Nikolenko wrote.
Meanwhile, a disputed ship has returned to Russian territorial waters, a Turkish source told AFP.
The Zhibek Zholy appeared to still be loaded, said the official, refuting a Russian media report suggesting that the ship's crew intended to offload the grain to another vessel before returning.
Turkey has halted a Russian-flagged cargo ship off its Black Sea coast on Sunday and started investigating a Ukrainian claim that it was carrying stolen grain.