Last year (15) the Canadian rocker, 70, previously launched a scathing attack on the billionaire turned politician for using his song Rockin' in the Free World at political events.

The musician went so far as to say that if Donald asked him for approval he would refuse due to his disillusion with U.S. politics and inability to vote in American elections.

However now the veteran singer-songwriter says he has no problem with the controversial candidate using his songs as Donald's campaign team obtained the licence to do so from the American Society of Composers, Authors and Publishers.

"He actually got a licence to use it," Neil tells Reuters. "I mean, he said he did and I believe him. So I got nothing against him. You know, once the music goes out, everybody can use it for anything."

Neil was one of the first musicians to criticise Donald for using his hits, and stars including Sir Elton John, Adele and The Rolling Stones have since hit out at the 69-year-old politician for playing their hits to supporters before his speeches.

In June last year (15), he wrote on his Facebook page, "Had I been asked to allow my music to be used for a candidate - I would have said no. I am Canadian and I don't vote in the United States, but more importantly I don't like the current political system in the USA and some other countries."

The real-estate mogul responded by calling Neil a "hypocrite" and posting a picture of himself shaking hands with the rocker.

Neil, who resides in California and is backing U.S. Democratic Party hopeful Bernie Sanders for the presidency, says that there is no bad blood between him and Donald, as despite having permission to play Rockin' in the Free World at rallies he refrained from doing so after his protest.

"If the artist who made it is saying you never spoke to them, if that means something to you, you probably will stop playing it," he adds. "And it meant something to Donald and he stopped.

"The fact that I said I was for Bernie Sanders and then he didn't ask me to use Rockin' in the Free World doesn't mean that he can't use it."

After a series of victories in U.S. state primary elections, Donald has now all-but wrapped up the Republican nomination to contest America's presidential election in November (16).

His Democratic opponent is likely to be Hillary Clinton, who has earned an estimated three million more votes than Bernie Sanders in their party's primary contest.