US tech billionaire Elon Musk has been accused of spreading an apparently digitally-altered video of Vice President Kamala Harris on his social media platform X.

The video appears to have been altered from a campaign ad created by Harris' team.

The edited video was originally released as a parody by a conservative YouTuber on Friday.

It mimics Harris' voice saying, "I was selected because I am the ultimate diversity hire." It also says: "I am both a woman and a person of color. So if you criticize anything, I say you're both sexist and racist."

Musk, who owns X, formerly known as Twitter, reposted the video on Friday with a caption saying, "This is amazing." He failed to disclose that it was a parody.

US media and observers argue that his repost could be a violation of X's policies which state, "You may not deceptively share synthetic or manipulated media that are likely to cause harm."

In response, Musk posted a comment on X saying, "parody is legal in America."

A number of deepfake videos circulating on social media have been deemed one of the major talking points in the US presidential race.