Neil Young has revealed he fears being blacklisted after voicing his opinions on Donald Trump.

The Heart of Gold singer admitted he worries he will not be allowed into the United States as a result of expressing his thoughts on the current White House administration.

"When I go to play music in Europe, if I talk about Donald J. Trump, I may be one of those returning to America who is barred or put in jail to sleep on a cement floor with an aluminum blanket," Neil, 79, wrote on social media on Tuesday.

"If I come back from Europe and am barred, can't play my USA tour, all of the folks who bought tickets will not be able to come to a concert by me."

The Canadian national added he feared for America's freedoms under Trump's presidency.

"If the fact that I think Donald Trump is the worst president in the history of our great country could stop me from coming back, what does that say for Freedom?" Neil wrote.

"I love America and its people and its music and its culture."

Neil previously cancelled a free concert in Ukraine that he had planned as a European tour launch, citing safety concerns in the wake of Trump's contentious meeting with Ukrainian leader Volodymyr Zelenskyy on 28 February.