According to US media, a letter sent to Elon Musk's political committee by the US Department of Justice warns that his lottery giveaway of $1 million a day to a registered voter may be illegal.
Mr Musk, who is the world's richest man, has been a vocal supporter of Republican Donald Trump in his presidential race against Kamala Harris.
Over the weekend, the owner of Tesla and X/Twitter began handing out prizes to American voters who signed the petition.
It is unclear when the Justice Department letter was sent to Mr. Musk's organization, America PAC. Justice Department investigators declined to comment on the case.
Mr Musk, who is the world's richest man, has been a vocal supporter of Republican Donald Trump in his presidential race against Kamala Harris.
Over the weekend, the owner of Tesla and X/Twitter began handing out prizes to American voters who signed the petition.
It is unclear when the Justice Department letter was sent to Mr. Musk's organization, America PAC. Justice Department investigators declined to comment on the case.
