Russia demanded that Ukrainians in the besieged city of Mariupol lay down their arms on Monday in exchange for safe passage out of town.
Ukraine has rejected the offer.
The demand came hours after Ukrainian authorities said Moscow’s forces bombed an art school that was sheltering about 400 people.
Western military analysts say that even if the city is taken, the troops battling for control there may be too depleted to secure Russian breakthroughs on other fronts.
Three weeks into the invasion, many see the conflict shifting to a war of attrition, with bogged down Russian forces launching long-range rockets as Ukrainian forces carry out hit-and-run attacks.
Analysts warn a stalemate could be even deadlier.
Russian forces would allow two corridors out of the coastal city, heading either east toward Russia or west to other parts of Ukraine, the Russian news agency Tass reported.
It cited a statement from Colonel-General Mikhail Mizintsev, head of the Russian National Defence Control Centre.
Tass reported that Mariupol residents had been given until 5am on Monday to respond to the offer.
But Ukrainian deputy prime minister Irina Vereshchuk rejected the notion.
“There can be no talk of any surrender, laying down of arms.
“We have already informed the Russian side about this,” she told the news outlet Ukrainian Pravda.
“I wrote: ‘Instead of wasting time on eight pages of letters, just open the corridor.”
Previous bids to allow residents to evacuate Mariupol and other Ukrainian cities have failed or have been only partially successful, with bombardments continuing as civilians sought to flee.
