US President Donald Trump said Monday he would launch a ?major investigation? into his 2024 election rival Kamala Harris over celebrities who backed her failed run for the White House.

?Candidates aren?t allowed to pay for ENDORSEMENTS, which is what Kamala did, under the guise of paying for entertainment,? he posted on his Truth Social platform.

?I am going to call for a major investigation into this matter.?

Harris sought to harness star power from celebrities such as Beyonce and Oprah Winfrey in the election race.

Winfrey defended a $1 million payment to her production company from the Harris campaign to covers costs associated with the talk show legend hosting the presidential candidate.

Harris?s team, meanwhile, denied rumours that she paid pop megastar Beyonce $10 million to appear at a rally.

The Harris campaign listed one endorsement-related expenditure for $75 in its financial reports to an environmental advocacy group.

Trump, who won the election comfortably, received scant support from the entertainment industry at large but tapped into a targeted subset of well-known, hypermasculine influencers including podcast host Joe Rogan.

The president on Monday took aim at Beyonce, Winfrey and Bruce Springsteen, accusing Harris of paying the legendary rock star to perform at a rally in Georgia weeks before the election.

?How much did Kamala Harris pay Bruce Springsteen for his poor performance during her campaign for president?? he wrote.

?Why did he accept that money if he is such a fan of hers??

Trump last week took to Truth Social to feud with Springsteen after the star told a British concert audience that his homeland is now ruled by a ?corrupt, incompetent and treasonous administration.?

In return, the 78-year-old Republican said the star, nicknamed ?the Boss,? is ?Highly Overrated.?

Springsteen is an outspoken liberal critic of Trump and turned out for Harris after she replaced Democratic president Joe Biden in his abandoned reelection bid. (AFP)

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