Russian and Ukrainian negotiators are to sit down for a fresh round of talks next week in an attempt to end the war in Ukraine that the UN estimates has killed at least 1,100 civilians and sent more than 3.8 million fleeing to other countries.
Kyiv said the negotiations would start Monday in Turkey, while Russia's lead negotiator said they would begin on Tuesday without confirming the location.
The prospect of fresh talks comes after the Russian army said last week that it would focus on eastern Ukraine, which some interpreted as a scaling back of Russian objections, although US President Joe Biden cast doubt on a strategy change.
France's President Emmanuel Macron on Sunday warned against an escalation "in words and action", after Biden on Saturday branded Russian President Vladimir Putin a "butcher" who "cannot remain in power".
The Kremlin reacted in fury to Biden's comments, saying it narrowed the window for bilateral relations, with the West and Moscow already at loggerheads over crushing sanctions imposed against Russia for invading Ukraine on February 24.
Rounds of diplomatic efforts and the sanctions have so far failed to get Putin to halt his war, despite the Russians appearing to run into tactical and logistical problems.
Ukraine's intelligence chief Kyrylo Budanov said Putin might be considering a Korean scenario, by seeking to "impose a separation line between the occupied and unoccupied regions of our country".
"After a failure to capture Kyiv and remove Ukraine's government, Putin is changing his main operational directions. These are south and east," he wrote on Facebook.
"In fact, it will be an attempt to set up South and North Koreas in Ukraine," Budanov added.
Russia may try to establish a quasi-state of occupied zones with its own currency, he assessed, but he vowed that Ukrainian counter-offensive will foil those plans.
Russia has de facto control over the self-proclaimed Donetsk and Lugansk republics in the country's eastern Donbas region.
The head of Ukraine's Lugansk separatist region said it may hold a referendum on becoming part of Russia — a move immediately slammed by Kyiv.
Russian troops have also been besieging Mariupol as taking the strategic port city would give Moscow an unbroken control stretching from the Donbas to the Crimea peninsula, which it annexed in 2014.
Ukraine was making a new push to get civilians out of the city on Sunday, with an aid route agreement for people to leave by cars or on evacuation buses, said Deputy Prime Minister Iryna Vereshchuk.
Several attempts at establishing safe routes for the 170,000 civilians trapped in the city to flee have collapsed as both sides trade blame for violating temporary ceasefires.
The French leader said he saw his task as "achieving first a ceasefire and then the total withdrawal of (Russian) troops by diplomatic means."
"If we want to do that, we can't escalate either in words or actions," he told broadcaster France 3, moving to dial down Biden's blunt words against Putin.
Putin sent troops into Ukraine, vowing in late February to destroy the country's military and topple pro-Western President Volodymyr Zelensky.
But his army has made little progress on capturing key cities, and it has hit hospitals, residential buildings and schools in increasingly deadly attacks on civilians.
Armed with Western-supplied weapons, Ukraine's fighters continue to hold back Russia's far-bigger military on the frontlines, and some units are beginning to snatch back control.
At the southern town of Mykolaiv, which had come under heavy Russian assaults for weeks, the bombardments appeared to be easing.
Sofia, who was hit in the head by shrapnel during shelling on March 5 in a village near Mykolaiv, hopes to soon be able to leave hospital, which moved several of its units underground amid the strikes.
"Now I can move my arms and legs a little, I still can't get up without my mother's help, but hopefully I can leave soon," she told AFP .
The frontlines appeared to have receded from Mykolaiv, with a counter-offensive being mounted now in Kherson, about 80 kilometres (50 miles) to the south-east.
Two people were killed by shelling at a village near Kherson, which has so far been the only significant city that the Russian army has claimed to have seized.
In Kherson itself, around 500 people shouted "Kherson, that's Ukraine" at new anti-Russian demonstrations on Sunday.
Kyrylo, a paramedic who spoke with AFP by telephone, said the peaceful rally was "dispersed twice" with tear gas and stun grenades.
The Ukrainian defence ministry said its forces had also recaptured Trostianets, a town near the Russian border that was one of the first to fall under Moscow's control.
Images published by the ministry showed Ukrainian soldiers and civilians among heavily damaged buildings and what appeared to be abandoned Russian military equipment.
On the eastern outskirts of Kharkiv, a Holocaust memorial at Drobytskyi Yar commemorating 15,000 Jews murdered by the Nazis in World War II was damaged by Russan shelling.
Bombardments continued in Irpin, as well as other areas around Kyiv, said Ukrainian authorities.
Tamara Osypchuk, 72, told AFP she wrote poetry to calm herself in her Irpin apartment when the bombs rained down.
"The explosions were very strong. Like a volcano is exploding, as if the earth explodes," she said as she rested on a chair at an evacuation centre on the outskirts of Kyiv.
Away from the battlefields, Ukrainian leaders pushed the fight on the economic front, with Foreign Minister Dmytro Kuleba calling for a boycott of French retailer Auchan.
"If Auchan ignores 139 Ukrainian children murdered during this month of Russian invasion, let us ignore Auchan and all their products," he wrote on Twitter.
Household names from McDonalds' to Volkswagen to Coca-Cola have left Russia in droves as unprecedented Western sanctions were imposed on Putin's country in a bid to stop his war in Ukraine.
The sanctions which personally target Putin, Russian government officials and oligarchs, will "cut in half" the Russian economy in the coming years, Biden said on Saturday.
