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Mr Zelenskyy renewed calls for heavy weapons from foreign partners, saying the billions of dollars' worth already put up were not enough to help Ukraine's outgunned forces.
“Unity is about weapons," he said during a panel discussion on Ukraine at the World Economic Forum. "My question is, is this unity there in practice? I can't see it. Our huge advantage over Russia would be when we are truly united."
As Mr Zelenskyy spoke to leaders in Davos, Russia accused Ukraine of setting mines at its ports, claiming this was worsening a world food crisis.
Mr Zelenskyy said Ukraine was grateful for US support but urged Europe to step up its efforts.
“We are on the European continent and we need the support of a united Europe,” he said. “Hungary is not as united as the rest of EU.”
He highlighted a lack of consensus over Sweden and Finland's bid to join Nato, which has been called into question by Turkey.
“Is there this unity regarding the accession of Finland and Sweden to Nato? No, no," he said. "So, is there a strong joint West? No.”
Turkish President Tayyip Erdogan has said he will launch a new military operation along his country's southern borders, raising the stakes in a spat with the two Nato hopefuls, which Ankara has long accused of harbouring members of the Kurdish militant PKK group.
Swedish Prime Minister Magdalena Andersson rejected such claims.
"We are not sending money to terrorist organisations, of course, nor any weapons," she said in Stockholm.
The Ukrainian president said hours earlier, in his daily address to the nation, that Russian forces “want to destroy everything” in eastern Ukraine, including the town of Soledar, a salt manufacturing centre.
Russia is now focused on expanding its gains in eastern Donbas, home to pro-Russian separatists, as well as the southern coast.
A swathe of southern Ukraine, meanwhile, is living under Russian occupation.
Mr Zelenskyy said the Kremlin should pull back its troops to their positions before the invasion to show it is ready to resume talks, even as Russia amassed forces for an offensive near the city of Zaporizhzhia and continued attacks in the Donbas region.
President Vladimir Putin has signed a decree simplifying a procedure to obtain a Russian passport for residents of the southern Ukrainian regions of Kherson, under the full control of Russian troops, and the partly-occupied Zaporizhzhia.
In Moscow, Russian Defence Minister Sergei Shoigu made it clear Russia was settling in for a long conflict.
“We will continue the special military operation until all the objectives have been achieved,” he said.
Tough sanctions imposed since Russia's invasion on February 24 are causing food shortages around the world, Moscow said.
Russian deputy foreign minister Andrey Rudenko said: “Solving the food problem requires a comprehensive approach, including the removal of sanctions that have been imposed on Russian exports and financial transactions."
Russia also demanded that Ukraine demine its ports.
The West argues it is Russia's offensive in Ukraine and blockade of ports that has pushed global food prices to an all-time high, sparking fears of worsening hunger, particularly in Africa.
Vital supplies such as water are running short in Ukraine itself as Moscow's war grinds on.