White nationalist Richard Spencer, who came to national prominence in the US through his efforts to lend a respectable face to a racist political movement dubbed the “alt-right”, has apparently been caught on tape using racist slurs against African Americans and Jewish people.

The expletive-laden audio recording was released on Sunday by former Breitbart writer, Milo Yiannopoulos, on YouTube amid deepening in-fighting on the far right.

The leaked audio, supposedly recorded in the immediate aftermath of the Unite the Right rally in Charlottesville in 2017 and the murder of anti-Nazi protester Heather Heyer, appears to feature an angry Spencer ranting against Charlottesville citizens and promising to return to the city for further protests.

On the recording, the voice continues: “Little fucking kikes. They get ruled by people like me. Little fucking octaroons. My ancestors fucking enslaved those little pieces of fucking shit.”

Later, he continued, “Those pieces of shit get ruled by people like me. They look up and see a face like mine looking down at them.”

Spencer popularized the term “alt right” to describe a politics that combined racist white nationalism, isolationism and criticism of mainstream conservatism. Alt Right support for the 2016 Trump campaign, and Spencer’s cultivation of a superficial civility – largely avoiding crude slurs and the markers of previous neo-Nazi subcultures – allowed Spencer to gain media coverage and a hearing in some mainstream outlets. As recently as July 2019 Spencer was interviewed on CNN.

Presented with a partial transcript by the Guardian, Spencer claimed not to recall making any such remarks, and said he would issue a statement and “get to the bottom of this” on Monday.

“I’ve listened to it. I’ll be responding today in video form this afternoon. I’m responding on my own. Not through the press,” he said via text. He declined to deny that the voice in the video was his.

Spencer also later tweeted a link to a rightwing video titled: Never Apologise.

Asked how he came by the recording, Yiannopoulos said via email that: “It was recorded by someone whose identity I have verified, and who I have placed where/when they said they recorded it. A second witness remembers the rant and remembers that person being present, and three others who have known Spencer for years confirm the voice is unmistakably his.”

Asked if the Guardian could be put in touch with his sources to confirm this information, Yiannopoulos said: “I’m not inclined to go out of my way for a publication that lies so outrageously and so often about me and so many of my friends.”

Last year, the Guardian reported that Yiannopoulos was some $2m in debt.

Unlike Spencer, who still has a Twitter account, Yiannopoulos has been deplatformed from many social media services. But on his channel on the messaging service, Telegram, Yiannopoulos repeated his claims about sourcing, and added: “I have always publicly hated Spencer, and he has always publicly hated me.”

The recording, released on YouTube, is prefaced with an extract from a recent interview in which Spencer criticizes white nationalist YouTuber, Nick Fuentes. Fuentes and Spencer have criticized one another repeatedly this year.