Image source, ReutersImage caption, Elon Musk is critical of a "billionaires tax" being proposed by some Democrats

Tesla billionaire Elon Musk has launched a Twitter poll of his 62.6 million followers asking if he should sell 10% of his shares.

The vote, which closes later on Sunday, could see him dispose of $21bn (£16bn) of stock in the electric carmaker.

He promised to abide by the result of the poll, a response to a "billionaires tax" proposed by US Democrats.

The plan could see Mr Musk, who is one of the world's richest men, face a huge tax bill.

By late morning on Sunday, with about 8 hours to go before the poll closes, 57% of the 2.8 million respondents had voted "yes".

The Tesla chief executive owns more than $200bn worth of shares and is due to exercise options next year that will boost his worth even further, but leave Mr Musk with what he said would be a "massive" tax bill.

Under plans proposed by the Democratic Party in the Senate, billionaires could be taxed on "unrealised gains" when the price of their shares goes up – even if they do not sell any of their stock.

In another tweet on Saturday, Mr Musk said: "Note, I do not take a cash salary or bonus from anywhere. I only have stock, thus the only way for me to pay taxes personally is to sell stock.

"Much is made lately of unrealized gains being a means of tax avoidance, so I propose selling 10% of my Tesla stock," he tweeted.

It is thought the proposed tax on capital gains, whether or not assets have been sold, could hit about 700 billionaires in the US. Critics have pointed out that the value of assets do not always go up.

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Mr Musk has an option, which expires in August next year, to buy 22.86 million Tesla shares at $6.24 each – a fraction of Tesla's closing share price on Friday of $1,222.

He recently said that he would sell $6bn in Tesla stock and donate it to the World Food Program, provided the organisation disclosed more information about how it spent its money.

The poll has raised some eyebrows in the world of finance. "We are witnessing the Twitter masses deciding the outcome of a $25B coin flip," Venture investor Chamath Palihapitiya wrote on Twitter.

"Looking forward to the day when the richest person in the world paying some tax does not depend on a Twitter poll," Berkeley economist Gabriel Zucman tweeted.

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To play this video you need to enable JavaScript in your browser.Media caption, Who is Elon Musk? Meet the meme-loving magnate behind SpaceX and Tesla