Austin, Texas - Billionaire Elon Musk has said a tweet about buying Manchester United was part of a "long-running joke."

The Tesla founder made reference to UK soccer club Manchester United in a late-night tweet.

Musk wrote: "To be clear, I support the left half of the Republican Party and the right half of the Democratic Party!"

"Also, I'm buying Manchester United ur welcome."

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His post quickly garnered a lot of attention, receiving more than 36,000 retweets and almost 200,000 likes within a couple of hours.

Many responded to the Tesla owner asking if he was serious. Musk tweeted in reply: "No, this is a long-running joke on Twitter. I'm not buying any sports teams."

Manchester United have been owned by the Florida-based Glazer family since 2005.

Their ownership has regularly come under fire from fans due to the debt, dividends, and mismanagement that followed their controversial takeover.

The Glazers have also overseen a sharp decline in performances and results in recent years.

The record 20-time champions of England have not won a Premier League title since Sir Alex Ferguson's final season in charge in 2012-13, and they haven't won a major trophy in five years.