A senior journalist at The Herald has apologised for describing ethnic minority MPs promoted to top jobs in the UK government as “the coconut cabinet”.

Iain Macwhirter, a former BBC political correspondent and one-time rector of Edinburgh University, has been told his longstanding column in the newspaper has been suspended during an investigation into a tweet.

He sparked a social media backlash for posting the tweet as a comment on Liz Truss’s decision to appoint the first cabinet in history in which none of the great offices of state are held by white men.

Kwasi Kwarteng, the son of Ghanian immigrants, is the new Chancellor. James Cleverly, whose mother was from Sierra Leone, was appointed Foreign Secretary, and Suella Braverman, whose mother was born in Mauritius, is Home Secretary.

The row kicked off after Tim Bale, professor of politics at Queen Mary, University of London, tweeted: “Folk (including @BBCr4today) are (rightly!) celebrating diversity in the ‘great offices of state’. But it’s maybe worth noting Kwarteng, Cleverly, and Braverman were all privately educated. Fact is that, nowadays, the real lack of diversity in Parliament is class-based.”

Mr Macwhirter, who is a regular political commentator on the BBC, responded: “The coconut cabinet?”

The term is regarded as a derogatory term which implies people of colour are white on the inside.

One respondent to Mr Macwhirter’s comment tweeted: “It’s 2022 and bold as brass you’re calling people coconuts on social media. Absolutely shameless racism, not even embarrassed — disgusting.”

Shirley Brown, a black Liberal Democrat councillor in Bristol, was convicted of racial harassment for describing Jay Jethwa, a black Conservative councillor, as a “coconut” in 2010.

Mr Macwhirter deleted his tweet and apologised. He said: “Earlier, I made an ironic reference to a term used by some on the left about black people who are deemed traitors to the cause through joining the Tory Party.

“After I posted it, I realised this joke might give offence and deleted it. It was unacceptable language, wide open to misinterpretation, and I am sincerely sorry for the distress I have caused.

“I have repeatedly applauded the Conservatives for having the most diverse cabinet in British history. Indeed, I tweeted earlier that the Truss cabinet made the Scottish government look ‘hideously white’.

“I have always championed racial diversity in my columns and I am dismayed that my cack-handed attempt at humour suggested otherwise.”

The controversy follows The Herald‘s recent appointment of its first female editor – Catherine Salmond – in its 239-year history.

The Herald said: “We are aware of an offensive tweet by one of our freelance contributors, Iain Macwhirter. Although the tweet has since been deleted and an apology issued, we have also suspended his columns while we investigate further.”

Macwhirter is a founder-member of the Free Speech Union Scotland, which was established to oppose the emergence of cancel culture.