Ukrainian President Volodymyr Zelensky has called on Russian soldiers to surrender.
In his nightly TV address, he said Russian forces had suffered worse losses during their invasion of his country than in the Chechnya conflict.
He said they had already begun to understand that they would not achieve anything by war.
"I know that you want to survive," he said, adding that those who surrendered would be treated "as people, decently".
Mr Zelensky also paid tribute to Marina Ovsyannikova, the woman who interrupted Russian state TV news by holding up an anti-war sign.
He said he was "grateful to those Russians who do not stop trying to convey the truth" and who fought disinformation.
Negotiations between Russia and Ukraine are expected to continue later, with Mr Zelensky saying "pretty good" progress had been made so far.
In another diplomatic move, the Polish, Czech and Slovenian prime ministers will visit Kyiv on Tuesday to meet Mr Zelensky.
The Polish government said in a statement that the visit was intended "to confirm the unequivocal support of the entire European Union for the sovereignty and independence of Ukraine and to present a broad package of support for the Ukrainian state and society".
However, authorities in the beleaguered capital have announced a 35-hour curfew to begin at 20:00 local time on Tuesday.
Kyiv mayor Vitali Klitschko said it would last until 07:00 on Thursday, adding that it came at "a difficult and dangerous moment".
Addressing the Russian invaders, Mr Zelensky said: "We hear your conversations in the intercepts, we hear what you really think about this senseless war, about this disgrace and about your state."
Therefore, he said, he was offering them a choice on behalf of the Ukrainian people.
"If you surrender to our forces, we will treat you the way people are supposed to be treated. As people, decently.
"In a way you were not treated in your army. And in a way your army does not treat ours. Choose!"