The Russian deputy foreign minister, Sergei Ryabkov, said the country would consider discussing an exchange of Azovstal prisoners.
Nearly 1,000 Ukrainian fighters who were at the besieged steelworks in Mariupol have surrendered and been handed over to Russian forces, according to the country’s defence ministry.
Ukraine has called for a prisoner swap in a bid to get the fighters back.
“Ukraine needs Ukrainian heroes alive,” said Volodymyr Zelensky in one of his nightly video addresses.
“Work continues to bring our lads home”, he added.
Vladimir Putin said the soldiers would be treated “in line with the relevant international laws”, although there are fears over what will happen to them if they remain in Russian custody.
One Ukrainian MP, Lesia Vasylenko, told the BBC that if they are not returned to Ukraine, “the fate of these very brave men will be absolutely unknown and will be in Russian hands, which is far from an ideal situation”.
The sprawling steelworks were the site of fierce fighting for the last few weeks.
Russia’s defence chief said on Friday the country’s forces had taken full control of the plant, which was the last stronghold of Ukrainian resistance in the city.
It marks the end of a nearly three-month siege that reduced much of Mariupol to ruins and left more than 20,000 people feared dead.