Meanwhile, Russian authorities said two people were killed and 11 injured in an overnight Ukrainian drone strike on Sochi, in Russia’s Krasnodar region.
Another Russian attack on the Ukrainian city Kharkiv on Thursday morning also left 33 injured.
Ukrainian and Russian delegations met on Wednesday evening in Istanbul in the third round of ceasefire talks.
Neither side appeared to harbour much hope for progress before start of the talks, which according to the head of the Ukrainian delegation lasted barely an hour.
The head of the Russian delegation, Vladimir Medinsky, said both countries agreed to swap 1,200 prisoners of war and that Russia had offered to transfer 3,000 bodies of fallen Ukrainian soldiers back to Kyiv.
But no tangible steps were taken to end the conflict, now well into its fourth year, and both sides accused the other of rejecting their ideas.
“We did not expect a breakthrough. A breakthrough is hardly possible,” said Kremlin spokesman Dmitry Peskov on Thursday.
Ahead of the meeting the head of the Ukrainian delegation, Rustem Umerov, said the “priority” for Kyiv was to organise a meeting between Russian President Vladimir Putin and Ukrainian President Volodymyr Zelensky before the end of August.