A police investigation has been launched into Brexit campaigner Darren Grimes over a controversial interview he published in which historian David Starkey said slavery was not genocide because there are "so many damn blacks" still around.
In a statement, Metropolitan Police confirmed that "on 4 July, the Metropolitan Police Service was passed an allegation from Durham Police of a public order offence relating to a social media video posted online on 30 June.
"The matter is currently being investigated."
No arrests have been made, the force added.
In the interview, which was published on YouTube channel Reasoned UK, Dr Starkey, 75, said: "Slavery was not genocide, otherwise there wouldn't be so many damn blacks in Africa or in Britain, would there?
"An awful lot of them survived and again there's no point in arguing against globalisation or Western civilisation. They are all products of it, we are all products of it.
"The honest teaching of the British Empire is to say, quite simply, it is the first key stage of our globalisation.
"It is probably the most important moment in human history and it is still with us."
In a statement to The Daily Telegraph, Mr Grimes said the police investigation had "serious repercussions for freedom of expression".
He told the paper: "At a time when many in our country are facing uncertainty and financial hardship, I cannot imagine a more contemptible way for the Metropolitan Police to abuse taxpayers' money and the trust of citizens (than) by investigating this vexatious claim."
In the wake of significant backlash from the interview, Dr Starkey resigned his honorary fellowship at Fitzwilliam College, Cambridge, while Canterbury Christ Church University terminated his role as visiting professor, calling his comments "completely unacceptable".
Dr Starkey issued a lengthy apology on July 6, in which he said his "principal regret" was that his "blundering use of language" could endanger people's right to freedom of speech.
Speaking about his use of the phrase "so many damn blacks", he said: "It was intended to emphasise, in hindsight with awful clumsiness, the numbers who survived the horrors of the slave trade.
"Instead, it came across as a term of racial abuse.
"This, in the present atmosphere, where passions are high and feelings raw, was deplorably inflammatory.
"It was a bad mistake. I am very sorry for it and I apologise unreservedly for the offence it caused."
Among those to speak out against Dr Starkey's comments was former Chancellor Sajid Javid, who said his remarks were "a reminder of the appalling views that still exist".