A Liberal Democrat staffer has been forced to apologise after he claimed that Labour’s Dawn Butler invented her experience of racial discrimination in parliament.

The shadow equalities minister wrote to the Lib Dem leader, Jo Swinson, asking for the suspension of Steve Wilson. He had criticised Butler on Twitter by saying her account of being confused for a cleaner in a lift in parliament because she was black was was “just not true” and she should stop “propagating” such “stories”.

Wilson is an office manager for his wife, the former Labour MP Angela Smith, who was briefly part of the Change UK grouping and drew controversy shortly after its foundation by saying people from black, Asian and minority ethnic backgrounds had a “funny tinge” during an appearance on the BBC Two programme Politics Live. She subsequently said she had misspoken and apologised.

Butler told the Guardian: “White men denying our lived experiences and accusing those of us who speak out about them of lying legitimises and promotes racism. This isn’t a ‘story’. This is race discrimination in the workplace; it is experienced by black, Asian and ethnic minority people in workplaces across our country every single day and we need to stamp it out.”

Butler wrote about her experience of being a black woman in politics when she first entered parliament in an opinion piece for the Metro as part of Black History Month.

She wrote: “I was naive when I first entered parliament; I thought everyone believed in equality and all would be treated with respect. I still remember the shock when I got in a lift and was told that ‘this lift isn’t for cleaners’. It stunned me. Such blatant racism from elected members of parliament stopped me in my tracks. But being one of only two black women elected to parliament and with so many privileged white men in one place, when I look back it shouldn’t have been surprising.”

In a reply to a post Butler made on Twitter sharing the article, Wilson wrote: “Sorry but this is just not true. I’ve worked in parliament for 15 years and the lifts have always been for the use of everyone. Only time MPs have priority is during a division. Stories like this don’t do anyone any justice and anyone propagating then [sic] should stop it.”

Wilson made his apology after being contacted by the Guardian.

Smith defected to the Lib Dems in September after quitting Labour to form Change UK. The outspoken critic of Jeremy Corbyn has represented Penistone and Stocksbridge since 2010 and has been in parliament since 2005.

She has announced she will run in Altrincham and Sale West at the next election, challenging the chair of the Tory 1922 committee, Sir Graham Brady, and Wilson has been actively campaigning for her.

Butler, who is one of Corbyn’s closest allies, said Smith’s husband needed to be immediately investigated by the Lib Dems.

She said: “I urge Jo Swinson to investigate … and take firm disciplinary action against this disgraceful gaslighting behaviour.”

A Labour source said: “The Lib Dems should immediately suspend him and fully investigate.”

Butler has reported the incident to House of Commons authorities to ask for them to investigate, as well as to Swinson.