Ukraine President Volodymyr Zelensky has hit back at Elon Musk after the Tesla boss posted a Twitter poll with his suggestions for ending Russia's invasion.
Mr Musk asked his 107.7 million followers to vote on ideas that included ceding territory to Russia.
In response Mr Zelensky posted his own poll asking users if they liked the world's richest person more when he supported Ukraine.
Other Ukrainians criticised Mr Musk.
Ukraine's outgoing ambassador to Germany, Andrij Melnyk, used a strong expletive, which he described as his "very diplomatic reply".
Meanwhile, Russian chess grandmaster Garry Kasparov said: "This is moral idiocy, repetition of Kremlin propaganda, a betrayal of Ukrainian courage & sacrifice."
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Mr Musk's ideas included votes in parts of Ukraine occupied by Russia that the Kremlin says it is annexing.
The multi-billionaire said: "Russia leaves if that is will of the people."
President Vladimir Putin has already declared four Ukrainian regions to be part of Russia, following so-called referendums denounced as fraudulent by Kyiv and its Western allies. Russia does not fully control any of the four regions.
Mr Musk also suggested the world should formally recognise Crimea - annexed by Russia in 2014 - as part of Russia. And the world's richest person in 2022, according to Forbes magazine, cautioned that the conflict could end in nuclear war, though added this was "unlikely".
After being posted for 10 hours Mr Musk's poll had attracted more than two million votes.
Mr Zelensky responding with his own poll asking: "Which @elonmusk do you like more? One who supports Ukraine [or] One who supports Russia."
Eight hours after it was posted, that poll had been voted on more than 1.5 million times.
Earlier in Russia's invasion Mr Musk's satellite internet company sent equipment to Ukraine.
That gained Mr Musk popularity in Ukraine and he was subsequently invited by Mr Zelensky to visit when the war with Russia was over.
The businessman posted his poll during a busy week when he is due to give evidence to lawyers acting for Twitter ahead of a trial set to begin on 17 October. Twitter is suing Mr Musk after he walked away from a $44bn deal to buy the social media platform.
Twitter is hoping the court in Delaware will order Mr Musk to complete the takeover at the agreed price of $54.20 per share.