Russian forces struck cities in eastern Ukraine and massed armoured vehicles and artillery near the capital Kyiv on Tuesday, as Western powers promised further sanctions to bring down Russia's economy.
On the sixth day of Russia's invasion, officials in Ukraine's second city, Kharkiv, said the Russian army had shelled the local administration building.
An AFP reporter saw the windows of the building were blown out and there was rubble all around it.
Local authorities in Mariupol on the Azov Sea also said their city was without power after bombing.
In Kherson on the Black Sea, Russian army checkpoints were reported at city entry points.
"The mask has finally dropped. Russia is actively shelling city centres, directing missiles and shells directly at residential areas and government buildings," an adviser to Ukrainian President Volodymyr Zelensky said on Twitter.
"Russia's aim is clear -- mass panic, civilian victims and the destruction of infrastructure. Ukraine is valiantly fighting back," wrote the adviser, Mykhailo Podolyak.
More than 350 civilians have been killed in the fighting and hundreds of thousands of Ukrainians have fled into neighbouring countries.
Russia has defied mounting global pressure and international pariah status to press ahead with its invasion and initial ceasefire talks between Moscow and Kyiv on Monday failed to secure a breakthrough.
Russian Defence Minister Sergei Shoigu on Tuesday said Russia would continue its offensive "until set goals are achieved".
He vowed to "demilitarise and de-Nazify" Ukraine and protect Russia from a "military threat created by Western countries".
Western powers are planning ever more stringent economic sanctions.
"We will bring about the collapse of the Russian economy," French Finance Minister Bruno Le Maire told the Franceinfo broadcaster.
The British government warned Russian President Vladimir Putin could face prosecution.
Putin and his commanders "will be held accountable for any violations of the laws of war," Justice Secretary Dominic Raab told Sky News.
'Bombing kept us up all night'
As the conflict intensifies, fears are growing of even higher casualties if Russian forces launch an offensive to try and take Kyiv -- a city of 2.8 million.
Satellite images showed a long build-up of armoured vehicles and artillery starting 29 kilometres (18 miles) north of the city.
The column is more than 65 kilometres long and covers the entire road from near Antonov airport outside Kyiv to the town of Prybirsk, US satellite imaging company Maxar said.
"Some vehicles are spaced fairly far apart while in other sections military equipment and units are travelling two or three vehicles abreast on the road," Maxar said.
In the city, makeshift barricades dotted the streets and residents formed long queues outside the few shops with essentials that remained open.
"We will greet them with Molotov cocktails and bullets to the head," bank employee Viktor Rudnichenko told AFP. "The only flowers they might get from us will be for their grave."
In the village of Shaika near Kyiv, Natasha, 51, opened a canteen in the local church to feed soldiers and volunteers.
"The shelling and the bombing kept us up all night," she said.
More than 660,000 people have already fled abroad, the UN refugee agency said Tuesday, with neighbouring Poland alone having taken in nearly 400,000 people.
Iryna Plakhuta, a pregnant 43-year-old executive, had to leave her family behind in the capital because of fears over her safety.
"Our husbands stayed in Kyiv," she said. "They are protecting Ukraine. It's so hard."
Badr Tawil, 23, a student, was among a group of Israelis evacuated from Ukraine who landed on Tuesday at Ben Gurion airport outside Tel Aviv.
"We just woke up once and we heard the sounds around us. Bombs everywhere. So we decided to leave, just to leave Ukraine," he said.
War crimes probe
Putin announced his demands to bring the war to an end in a phone call with his French counterpart Emmanuel Macron on Monday.
They included recognition of Russian sovereignty over Crimea and Ukraine's demilitarisation.
Instead, Western nations have moved to increasingly isolate Russia, responding with an intensifying diplomatic, economic, cultural and sporting backlash.
The weekend featured a momentous series of announcements from Europe, with Germany unveiling a historic change to its defence policies.
The EU also said it would buy and supply arms to Ukraine, the first such move in its history.
Moscow came under fire on Monday at the UN General Assembly and the International Criminal Court (ICC), which opened a war crimes investigation.
Russia also faced urgent calls at an extraordinary UN General Assembly debate to end its "unprovoked" and "unjustified" assault.
Inside the General Assembly hall Monday, UN Secretary-General Antonio Guterres pleaded: "The fighting in Ukraine must stop. Enough is enough."
And Turkey said it would implement an international treaty to limit ships passing through the Dardanelles and Bosphorus straits, a move requested by Ukraine to block the transit of Russian warships.
The Russian ruble crashed to a record low as sanctions imposed by the West over the weekend had an immediate impact in Moscow, forcing the central bank to more than double its key interest rate to 20 percent.
Putin also announced emergency measures intended to prop up the ruble, including banning residents from transferring money abroad.
Many Russians raced to withdraw cash.
Retired soldier Edward Sysoyev, 51, fidgeted impatiently while in line at a bank in Moscow.
"Ninety percent of Russians are going to rush to withdraw their rubles and change them into dollars, property or even gold... it'll be ordinary people who pay for this military bun-fight," he said.
Russian conductor sacked
The response from the world of sports also gathered steam, as Russia was expelled from the World Cup and the country's clubs and national teams were suspended from all international football competitions "until further notice", FIFA and UEFA said.
The International Olympic Committee on Monday urged sports federations and organisers to exclude Russian and Belarusian athletes and officials from international events.
Authorities in badminton, rugby, ice hockey, basketball and Formula One have all moved to act against Russia, either banning Russian national teams and clubs, or suspending events in Russia.
In the latest developments, Russia was stripped of hosting the 2022 Volleyball World Championships, YouTube said it was blocking Russian channels RT and Sputnik in Europe and shipping giant Maersk said it would stop deliveries to Russian ports.
In the arts, the Munich Philharmonic said it was parting ways with star Russian conductor Valery Gergiev "with immediate effect" after he failed to respond to a request to denounce the invasion.