The panel, it said, appears to have reacted more to negative press coverage than the substance of its work. And a spokesman for the commission said the criticisms "risk fostering division on the subject of race, rather than constructive discussion on the issues".
A spokesperson for Johnson's office said it was considering how to follow up on the British commission's recommendations, which it said had the potential to promote equality.
But the UN panel's harsh verdict, which comes as Americans await the outcome of a trial in the Floyd killing, is an embarrassing blow for Johnson's approach to race from the UN human rights machinery as it prepares for a high-profile debate on racism in the Human Rights Council in June.
Britain's commission said in its report, released in March, that racism remained "a real force" in British society easily amplified by social media, but that discrimination in Britain was more a result of socio-economic inequities than ethnicity or skin colour.
"We no longer see a Britain where the system is deliberately rigged against ethnic minorities," the commission's chairman, Tony Sewell, said in a foreword to the report.
Among other major findings, the commission said that South Asian and Black African students consistently outperformed white students in compulsory education, arguing the school system had promoted social mobility and helped to transform British society over the past 50 years.
The report's defenders said it delivered new facts that helped puncture outdated myths and narratives about racial discrimination. But it also drew widespread criticism from groups working on racial issues, from academics and from Britain's opposition Labour Party. They said it set back discussions on racism and instead stoked division.
The five-member UN panel, led by American attorney and rights activist Dominique Day, and including human rights experts from the Caribbean, Africa and Asia, said the report drew on dubious evidence to rationalise white supremacy and ignored the findings of other UN panels and human rights experts.
It agreed that racial disparities may not always stem from racism or racial discrimination but asserted that "there is also compelling evidence that the roots of these disparities lie in institutional racism and structural discrimination as they clearly do not reflect the preferences or priorities of the communities facing structural disadvantage".
The panel aimed a scathing rebuttal at the British commission's attempt to draw positive lessons from slavery, or "the Caribbean experience", which the commission report said was not exclusively about profit and loss "but how culturally African people transformed themselves into a remodelled African/Britain".
This "mythical" representation of slavery, the panel said, was an attempt to sanitise history, and a deliberate misrepresentation.
Panel members urged the British government to categorically reject the commission findings, warning that its historical distortions and falsehoods "may license further racism, the promotion of negative racial stereotypes, and racial discrimination".
Yasmine Ahmed, Human Rights Watch's director in Britain, said the intervention by the UN panel made clear "just how much of a whitewash" the commission report was.
She said that institutional racism had been well established in the British policing, immigration and justice systems, and until the government acknowledges that, the country "cannot move forward".
Written by: Nick Cumming-Bruce
Photograph by: Andrew Testa
© 2021 THE NEW YORK TIMES