US rapper B.o.B has released a track downplaying the Nazi genocide, hinting at a Jewish conspiracy involving President Barack Obama and urging listeners to research Holocaust denier David Irving.

The song came after B.o.B - whose real name is Bobby Ray Simmons - posted dozens of tweets on Monday claiming that the Earth is flat.

At one point, the singer - who has number one singles in the UK and the US - wrote: “A lot of people are turned off by the phrase ‘flat earth’ ... but there's no way u can see all the evidence and not know... grow up”.

This rant elicited responses from prominent US astrophysicist Neil deGrasse Tyson, who tweeted back to inform the musician that he was mistaken, calling him “five centuries regressed” in his reasoning.

He explained: “Flat Earth is a problem only when people in charge think that way. No law stops you from regressively basking in it.”

The war of words escalated in the early hours of Tuesday morning when B.o.B released a song online called "Flatline," in which he accuses Mr Tyson of being paid to espouse his views.

B.o.B sang: "Neil Tyson need to loosen up his vest / They’ll probably write that man one hell of a check".

In the same song, the singer - who has collaborated with Taylor Swift and Paramore lead singer Hayley Williams - included other conspiratorial lyrics involving masons and "the mirror lizards" before telling listeners: "But before you try to curve it, do your research on David Irving.

“Stalin was way worse than Hitler / That’s why the POTUS (President of the United States) gotta wear a kippah.”

David Irving is a renowned British Holocaust denier who has spoken at numerous neo-Nazi rallies.

He has spent more than a year in jail in Austria for denying the Holocaust.