British intelligence warned that Russia, frustrated by its failure to achieve its objectives since it launched the invasion on February 24, was now pursuing a strategy of attrition that could intensify the humanitarian crisis.
Russian forces have taken heavy losses and their advance has largely stalled since President Vladimir Putin launched the assault, with long columns of troops that bore down on Kyiv halted in the suburbs.
But they have laid siege to cities, blasting urban areas to rubble, and in recent days have intensified missile attacks on scattered targets in western Ukraine, away from the main battlefields.
Zelenskiy, who makes frequent impassioned appeals to foreign audiences for help for his country, told an anti-war protest in Bern on Saturday that Swiss banks were where the "money of the people who unleashed this war" lay and their accounts should be frozen.
Ukrainian cities "are being destroyed on the orders of people who live in European, in beautiful Swiss towns, who enjoy property in your cities. It would really be good to strip them of this privilege," he said in an audio address.
Neutral Switzerland, which is not a member of the European Union, has fully adopted EU sanctions against Russian individuals and entities, including orders to freeze their wealth in Swiss banks.
The EU measures are part of a wider sanctions effort by Western nations, criticised by China, aimed at squeezing Russia's economy and starving its war machine.
In an address earlier on Saturday, Zelenskiy urged Moscow to hold peace talks now.
"I want everyone to hear me now, especially in Moscow. The time has come for a meeting, it is time to talk," he said in a video address.
"The time has come to restore territorial integrity and justice for Ukraine. Otherwise, Russia's losses will be such that it will take you several generations to recover."
Britain's Defence Attaché to the United States said British intelligence believes Russia has been taken aback by the Ukrainian resistance to its assault and has so far failed to achieve its original objectives.
"Russia has been forced to change its operational approach and is now pursuing a strategy of attrition" likely to involve the "indiscriminate use of firepower resulting in increased civilian casualties", Air Vice-Marshal Mick Smeath said in a statement.
Putin, who calls the action a "special operation" aimed at demilitarising Ukraine and purging it of what he sees as dangerous nationalists, told a rally on Friday in Moscow that all the Kremlin's aims would be achieved.
On Saturday, Russia said its hypersonic missiles had destroyed a large underground depot for missiles and aircraft ammunition in the western Ivano-Frankivsk region.
Hypersonic weapons can travel faster than five times the speed of sound and the Interfax agency said it was the first time Russia had used them in Ukraine.
The Ukrainian military command in charge of forces in two breakaway regions of eastern Ukraine said they had fought off 10 attacks on Saturday, destroying a total of 28 tanks, armoured personnel carriers and arnoured cars and killing more than 100 soldiers. Reuters was unable to independently corroborate the claim.
The United Nations human rights office said at least 847 civilians had been killed and 1399 wounded in Ukraine as of Friday, with the real figure likely much higher.
The Ukrainian prosecutor general's office said 112 children were among the dead. Russia says it is not targeting civilians.
Kyiv authorities on Saturday said 228 people had been killed in the capital since Russia's invasion began, including four children.
A further 912 people have been wounded, the Kyiv city administration said in a statement.
Reuters has not been able to independently confirm casualty figures.
