Tory MP Phillip Davies has been accused of having "a problem with the concept of racial equality".
Speaking in the Commons on Thursday, the Tory backbencher criticised the government for launching a review into the lack of ethnic minority directors in British boardrooms.
He accused Lib Dem business secretary Vince Cable of beng "in a league of his own as a politically corrrect champion that believes neither in merit nor in representation but believes that ethnic minorities should be overrepresented in the boardroom."
Cable had asked Trevor Phillips, former chair of the equality and human rights commission to lead a campaign to encourage firms to address the lack of ethnic minority directors in their boardrooms.
The Lib Dem cabinet minister said that he believed in appointments on merit rather than through quotas. Noting that Davies had written 19 letters to Phillips on the subject of race and political correctness, he said it led him to believe the Tory MP "might have a problem with the concept of racial equality".
He also said that he thought Davies would be in Rochester "waiting to defect" to Ukip, as voters are almost certain to elect Mark Reckless as the second Ukip MP today.
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Davies later accused Cable of holding "two different opinions at the same time" as he claimed the business secretary wanted a "quota" of having 20% of boardroom members coming from an ethnic minority background, which was "going too far".
According to official figures, 86% of the population in England and Wales in 2011 was white, 80.5% was white British, with the second-largest category classed as Asian or British Asian at 7.5%.
The Lib Dem cabinet minister reportedly wants to see one in five FTSE100 directors coming from non-white backgrounds in five years, but that is mooted as a target rather than a legally-binding quota.
"There is a problem, that I hope he would acknowledge, that over half of the boardrooms in the UK have no non-white representation whatever," he said. "One in sixteen senior managers come from ethnic minority backgrounds, and they should be better represented."
Davies' question led to a furious row later on Twitter with Labour's shadow business minister Stella Creasy, who questioned him on why he was concerned about "representation" in boardrooms and how he determined "merit".
"Anyone who thinks appointments done solely on merit & that accounts for lack of diversity obviously isn't very good at maths," she wrote.
Davies called her a "deeply unpleasant liar", insisting that he believed in "merit and merit alone" no matter what level of representation.