Sports Direct’s founder Mike Ashley has accused MPs of “showboating” and said he will challenge being formally summoned to a parliamentary select committee.

It is the latest episode in an increasingly heated battle between Ashley and the Business, Innovation and Skills Committee (BIS), which last week again said it wanted to question Ashley over Sports Direct working conditions and insisted he could be held in contempt of Parliament if he fails to attend the meeting at the House of Commons.

However, in a rare TV interview with Sky News, Ashley called MPs a “joke”, adding that they only care “about the business of politics, while I actually care about the people at Sports Direct”.

He added: “I do not pretend to get everything right all of the time, but I am not willing to stand idle while this company is subjected to public vilification, which is against the best interests of everybody who works at Sports Direct.

“My current intention is that I will not attend Westminster on June 7 as I believe the proposal by [BIS select committee chairman] Iain Wright MP – whom I have offered to meet in Shirebrook – is an abuse of the parliamentary process. I therefore intend to challenge the attendance order issued by the BIS committee and I will be sending a formal reply to the committee in due course.”

Ashley had invited Wright to Sports Direct’s head office in Shirebrook, but Wright declined, citing the “select committee’s commitment to transparency”.

The MPs are targeting Ashley after a Guardian investigation found workers in the retailer’s warehouse were effectively working below the minimum wage and that they were being subjected to extreme levels of searches and surveillance.