Ukraine on Saturday said Russian forces were making a "rapid retreat" from northern areas around the capital Kyiv and the city of Chernigiv as the Red Cross prepared for a fresh evacuation effort from the besieged southern port of Mariupol.
Ukraine said Russian forces were concentrating in the east and south, a day after thousands of people from Mariupol and surrounding Russian-held areas escaped in a convoy of buses and private cars.
"Russia is prioritising a different tactic: falling back on the east and south," Ukrainian presidential adviser Mykhaylo Podolyak said on social media.
He said that while Russian forces appeared to be pulling back from Kyiv and Chernigiv, their aim was to "control a vast stretch of occupied territory and set up there in a powerful way".
Podolyak said Russian forces would "dig in there, set up air defence, drastically reduce losses and dictate terms.
Moscow's aim was to "drastically reduce losses & dictate terms", he said on Twitter on Saturday.
"Without heavy weapons we won't be able to drive (Russia) out".
'Our city doesn't exist anymore'
Mariupol has been an important Ukrainian hold-out, suffering weeks of Russian shelling, with at least 5,000 residents killed, local officials said.
The estimated 160,000 who remain face shortages of food, water and electricity.
"We have managed to rescue 6,266 people, including 3,071 people from Mariupol," Zelensky said in a video address earlier on Saturday.
Dozens of buses carrying Mariupol residents who had escaped the devastated city arrived Friday in Zaporizhzhia, 200 kilometres (120 miles) to the northwest, according to an AFP reporter on the scene.
The buses carried people who had been able to flee Mariupol to Russian-occupied Berdiansk.
"We were crying when we reached this area. We were crying when we saw soldiers at the checkpoint with Ukrainian crests on their arms," said Olena, who carried her young daughter in her arms.
"My house was destroyed. I saw it in photos. Our city doesn't exist anymore."
The International Committee of the Red Cross (ICRC) said its team headed to Mariupol to try and conduct an evacuation was forced to turn back Friday after "arrangements and conditions made it impossible to proceed".
The ICRC said it would try again on Saturday.
New US aid
Peace talks between Kyiv and Moscow resumed via video on Friday, but the Kremlin warned that what it described as a helicopter attack on a fuel depot inside Russia would hamper negotiations.
"This is not something that can be perceived as creating comfortable conditions for the continuation of negotiations," Kremlin spokesman Dmitry Peskov told reporters.
The air strike hit energy giant Rosneft's fuel storage facility in Belgorod, 40 kilometres from the Ukraine border.
But Kyiv would not be drawn on whether it was behind the attack, with Zelensky telling US network Fox News: "I'm sorry, I do not discuss any of my orders as commander in chief."
He said Russia was consolidating and preparing "powerful strikes" in the east and south, joining Western assessments that Moscow's troops were regrouping, not withdrawing.
Ukraine also warned that Russian forces who left the Chernobyl nuclear plant -- site of the world's worst nuclear accident, in 1986 -- after weeks of occupation may have been exposed to radiation.
"Russia behaved irresponsibly in Chernobyl" by digging trenches in contaminated areas and keeping plant personnel from performing their duties, said Foreign Minister Dmytro Kuleba.
Zelensky meanwhile repeated his plea for the West to provide greater military support.
"Just give us missiles. Give us airplanes," he told Fox. "You cannot give us F-18 or F-19 or whatever you have? Give us the old Soviet planes. That's all... Give me something to defend my country with."
The Pentagon later said it was allotting $300 million in "security assistance" to bolster Ukraine's defence capabilities, adding to the $1.6 billion Washington has committed since Russia invaded in late February.
'Where roses used to bloom'
A ferocious Ukrainian fightback and Russia's logistics and tactical problems have hampered Russian efforts and there is growing concern inside the country as military losses mount.
Russia on Friday launched its annual military draft but vowed that conscripts would not be sent to fight in Ukraine.
Referring to the draft, Zelensky urged Russian families not to send their children to war.
"Don't let them join the army. It's not their war. We don't need any more deaths," he said.
Civilians have trickled out of devastated areas after arduous and daring escapes.
Three-year-old Karolina Tkachenko and her family walked an hour through a field strewn with burnt-out Russian armoured vehicles to flee their village outside Kyiv.
"The shops are closed, there's no delivery of supplies. The bridge is also blown up, we can't go for groceries through there," said Karolina's mother Karina Tkachenko.
In Mariupol, Viktoria Dubovytskaya, who had sheltered in the theatre where 300 people are feared to have been killed in Russian bombardments, said she only grasped the extent of the destruction as she fled.
Bodies lay in the rubble and small wooden crosses were planted in the ground, she told AFP.
"When people find their loved ones, they just bury them wherever they can. Sometimes where roses used to bloom," she said.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
