Ukraine's intelligence services are in communication with the captured Azovstal steelworks fighters, and Kyiv is doing all it can to ensure their release.
Ukrainian Interior Minister Denys Monastyrskiy said late on Friday.
Uncertainty has surrounded the fate of hundreds of fighters taken into Russian custody in mid-May after being ordered to stand down.
"It is through them (intelligence services) that we are learning about the conditions of the detention, nutrition and the possibility of their release," Monastyrskiy said on Ukrainian television.
"We all know that they will all be here, in Kyiv, and we are doing everything possible to do so."
Russia said in May that almost 2,000 Ukrainians had surrendered after making a last stand in the ruins of Mariupol, where they had held out for weeks in bunkers and tunnels beneath the vast Azovstal steelworks.
Kyiv wants the fighters returned in a prisoner swap. Some senior Russian lawmakers have demanded that some of the soldiers be put on trial. The Kremlin has said the fighters who surrendered will be treated according to international standards.
Israel and Iran attacked each other for a fifth straight day on Tuesday, and US President Donald Trump urged Iranians to evacuate Tehran, citing what he said was the country's rejection of a deal to curb nuclear weapons development.
Waves of Russian drones and missiles struck districts across the Ukrainian capital Kyiv early on Tuesday, killing 14 people and injuring 44, according to the interior ministry.
US President Donald Trump left the Group of Seven summit in Canada a day early due to the situation in the Middle East, the White House said on Monday.
Pro-Iranian demonstrations broke out for another night in Iraq on Monday, as Iranian-backed militias in the country threatened to attack US interests, and tit-for-tat strikes between Israel and Iran rolled into the fifth day on Tuesday.
The U.S. military has moved a large number of refueling aircraft to Europe to provide options to President Donald Trump as Middle East tensions erupt into conflict between Iran and Israel, two U.S. officials told Reuters on Monday, speaking on condition of anonymity.
Sheikh Abdullah bin Zayed Al Nahyan, Deputy Prime Minister and Minister of Foreign Affairs, held phone calls with numerous counterparts from around the globe, as the Israel-Iran conflict entered its fifth day on Tuesday.