Several countries have promised to send anti-armour and anti-aircraft missiles as well as small arms but Ukrainian President Volodymyr Zelenskyy said Kyiv needed tanks, planes and anti-ship systems.
"That is what our partners have, that is what is just gathering dust there. This is all for not only the freedom of Ukraine, but for the freedom of Europe," he said in a late-night video address.
Ukraine needed just one per cent of NATO's aircraft and 1 per cent of its tanks and would not ask for more, he said.
"We've already been waiting 31 days. Who is in charge of the Euro-Atlantic community? Is it really still Moscow, because of intimidation?" he said.
People are seen in a temporary accommodation facility for the evacuated in a local secondary school named after Donat Patrycha in the urban settlement of Nikolskoye (former Volodarskoye). Source: AAP / TASS/Sipa USA
Earlier in the day, Mr Zelenskyy talked to Polish counterpart Andrzej Duda and expressed disappointment that Russian-made fighter aircraft in Eastern Europe had not yet been transferred to Ukraine, Mr Zelenskyy's office said in a statement.
"The price of procrastination with planes is thousands of lives of Ukrainians," the office quoted him as saying.
Mr Zelenskyy said Poland and the United States had both stated their readiness to make a decision on the planes.
Earlier this month, Washington rejected a surprise offer by Poland to transfer MiG-29 fighter jets to a US base in Germany to be used to replenish Ukraine's air force.
It comes as Russian forces took control of a town where staff working at the Chernobyl nuclear site live and briefly detained the mayor, sparking protests, Ukrainian officials said.
"I have been released. Everything is fine, as far as it is possible under occupation," Yuri Fomichev, mayor of Slavutych, told AFP by phone, after officials in the Ukraine capital Kyiv announced earlier he had been detained.
A still image taken from a handout video made available by the Russian Defence Ministry press service shows a general view of the Chernobyl Nuclear Power Plant in Pripyat, Ukraine. Source: AAP / RUSSIAN DEFENCE MINISTRY PRESS SERVICE/HANDOUT HANDOUT/EPA
They also said that the mayor had been detained.
Residents took to the streets, carrying a large blue and yellow Ukrainian flag and heading towards the hospital, the administration said. Russian forces fired into the air and threw stun grenades into the crowd, it added.
It also shared on its Telegram account images in which dozens of people gathered around the Ukrainian flag and chanted: "Glory to Ukraine."
Later Saturday, Mr Fomichev posted a video on Facebook saying that at least three people had died, without elaborating on what had happened.
"We haven't yet identified all of them," he added, but said that civilians were among the dead.
While they had defended their town, they were up against a larger force, he said.
Putin 'cannot remain in power'
In Poland on Saturday, US President Joe Biden said that Russia's leader Vladimir Putin "cannot remain in power", remarks a White House official said later were meant to prepare the world's democracies for extended conflict over Ukraine, not back regime change in Russia.
Mr Biden's comments, including a statement earlier in the day calling Putin a "butcher," were a sharp escalation of the US approach to Moscow over its invasion of Ukraine.
In a major address delivered at Warsaw's Royal Castle, Mr Biden evoked Poland's four decades behind the Iron Curtain in an effort to build a case that the world's democracies must urgently confront an autocratic Russia as a threat to global security and freedom.
But a remark at the end of the speech raised the spectre of an escalation by Washington, which has avoided direct military involvement in Ukraine, and has specifically said it does not back regime change.
"For God's sake, this man cannot remain in power," Mr Biden told a crowd in Warsaw after condemning Putin's month-long war in Ukraine.
A White House official said Mr Biden's remarks did not represent a shift in Washington's policy.
"The President's point was that Putin cannot be allowed to exercise power over his neighbours or the region," the official said. "He was not discussing Putin's power in Russia, or regime change."
Asked about Mr Biden's comment, Kremlin spokesman Dmitry Peskov told news agency Reuters: "That's not for Biden to decide. The president of Russia is elected by Russians."
Calling the fight against Mr Putin a "new battle for freedom," Mr Biden said Mr Putin's desire for "absolute power" was a strategic failure for Russia and a direct challenge to a European peace that has largely prevailed since World War Two.
"The West is now stronger, more united than it has ever been," Mr Biden said. "This battle will not be won in days or months, either. We need to steel ourselves for the long fight ahead."
Mr Biden also cast doubt on to concentrate on eastern Ukraine, as two Russian missile strikes slammed into the west of the country on Saturday.
After failing to break Kyiv's ferocious resistance in a month of fighting and deadly attacks on civilians, the Russian army in a surprise announcement said it would focus on "the main goal — the liberation of Donbas".
But Mr Biden said he was "not sure" that Moscow has indeed changed strategy.
Mr Biden's assessment came as two missiles struck a fuel depot in western Ukraine's Lviv, a rare attack on a city just 70 kilometres from the Polish border that has escaped serious fighting since Russian troops invaded last month.
At least five people were wounded, regional governor Maksym Kozytsky said, as journalists from news agency AFP in the city centre saw plumes of thick black smoke.
Mr Putin sent troops into Ukraine on 24 February, vowing to destroy the country's military and topple Mr Zelenskyy.
But his army has made little progress on capturing key cities, and its attacks that have hit hospitals, residential buildings and schools have become more deadly.
Mr Biden, who has been leading efforts among Western allies to press Putin to end his invasion of Ukraine, over the assaults on civilians.
Smoke rises outside Lviv, Ukraine, after a Russian airstrike, on 26 March 2022. Source: AAP, EPA / Wojtek Jargilo
'Unwavering'
Mr Biden, who was on a two-day visit to Poland after holding a series of summits in Brussels with Western allies, earlier met Ukraine's Foreign Minister Dmytro Kuleba and Defence Minister Oleksii Reznikov in Warsaw in an emphatic show of support for Kyiv.
Both ministers had made a rare trip out of Ukraine for the face-to-face talks, in a possible sign of growing confidence in their fightback against Russian forces.
The talks discussed Washington's "unwavering commitment to Ukraine's sovereignty and territorial integrity," State Department spokesperson Ned Price told reporters.
Mr Biden, who later met Polish President Duda, also stressed the "sacred commitment" to NATO's collective defence, in a clear reassurance to Ukraine's neighbours rattled by the conflict.
"You can count on that... for your freedom and ours," he told Mr Duda.
Speaking after visiting Ukrainian refugees later Saturday, Mr Biden said he had been asked by children to pray for their male relatives fighting in Ukraine.
"I remember what it's like when you have someone in a war zone and every morning you get up and you wonder... you are praying you don't get that phone call," said Mr Biden, whose son Beau served in Iraq before dying of a brain tumour.
'Everybody's shooting'
On the frontlines, Russia's far-bigger military continued to combat determined Ukrainian defenders who are using Western-supplied weapons — from near the capital Kyiv to Kharkiv, the Donbas region and the devastated southern port city of Mariupol.
A humanitarian convoy leaving Mariupol, including ambulances carrying wounded children, was being held up at Russian checkpoints, a Ukrainian official said.
A buildup of several kilometres had formed close to Vassylivka, in the region of Zaporizhzhia where the convoy was headed, said Lyudmyla Denisova, in charge of human rights in Ukraine.
"The ambulances carrying wounded children are also queueing. The people have been deprived of water and food for two days," she wrote on Telegram, blasting Russian troops for "creating obstacles".
Authorities have said they fear some 300 civilians in Mariupol may have died in a Russian air strike on a theatre being used as a bomb shelter last week.
Russian forces hammering Mariupol's out-gunned resistance consider the city a lynchpin in their attempt to create a land corridor between the Crimea region, which Moscow seized in 2014, and the Donbas.
Ukrainian soldiers chat in the front line position close to Kharkiv, Ukraine, on Saturday, 26 March, 2022. Source: AAP, AP / Efrem Lukatsky
"I have lost all my family. I have lost my house. I am desperate," the 33-year-old told AFP after reaching Lviv by train.
"My mum is dead. I left my mother in the yard like a dog, because everybody's shooting."
In Kharkiv, where local authorities reported 44 artillery strikes and 140 rocket assaults in a single day, residents were resigned to the incessant bombardments.
Anna Kolinichenko, who lives in a three-room flat with her sister and brother-in-law, said they don't even bother to head down to the cellar when the sirens go off.
"If a bomb drops, we're going to die anyway," she said. "We are getting a little used to explosions".
Russian forces have taken control of Slavutych, the town where workers at the Chernobyl nuclear plant live, briefly detaining the mayor, regional Ukrainian authorities said.
Residents of the town protested, prompting the invading forces to fire shots in the air and lob stun grenades into the crowd.
Kyiv said it was shortening a planned 35-hour curfew to just Saturday 8pm to Sunday 7am, as Britain's defence ministry said Ukrainian counter-attacks were underway near the capital.
Ukrainian forces were also attempting to recapture Kherson, the only major city held by Russian invasion troops, a Pentagon official said.
