Neil Young wants Donald Trump to stop rocking out to one of his classic songs as part of the U.S. tycoon's bid for the Republican nomination.

The New York real estate mogul pumped Young's Rockin' in the Free World through Manhattan's Trump Tower as he launched his bid for the U.S presidency on Tuesday.

But Young, an outspoken environmental activist, says the businessman doesn't have permission to use the song.

"Donald Trump was not authorized to use Rockin' in the Free World in his presidential candidacy announcement," said an official statement from Young's representative, via Mother Jones.

"Neil Young, a Canadian citizen, is a supporter of Bernie Sanders for president of the United States of America."

Sanders is a Vermont Independent running for the Democratic nomination.

Trump's a 'huge' Young fan

Despite Young's insistence, a spokesperson for the Trump campaign says the candidate secured a licence agreement with the American Society of Composers, Authors and Publishers, or ASCAP.

"Mr. Trump's campaign paid for and obtained the legal right to use Neil Young's recording of Rockin' in the Free World," the spokesperson told Rolling Stone magazine.

"Mr. Trump is a huge fan of Neil Young and his music and will continue to be regardless of Neil's political views."

However, ASCAP rules are different for political campaigns, and politicians are urged to ask for the artist's permission.

It would appear that Trump failed to secure Young's approval.

Despite Trump's taste for the Canadian rocker's songs, Rockin' in the Free World is an an odd choice for the billionaire businessman and reality TV capitalist.

It's believed that Young wrote the 1989 anthem as an indictment of the politics of U.S. President Ronald Reagan and the widespread consumerism of American culture.