It was leaked alongside a cache of emails that detail the correspondence between Mr Yiannopoulos, 32, Steve Bannon, the editor of Breitbart, and known white supremacists.

Buzzfeed claims the emails show that Mr Bannon promoted Mr Yiannopoulos to fight a “war” against political liberalism and to define the movement later called the "alt-right" in the early stages of the US election campaign.

The footage was filmed in Dallas in April 2016 and shows Mr Yiannopoulos singing America the Beautiful at the One Nostalgia Tavern.