Tendayi Achiume, the UN’s special rapporteur on racism, also said Brexit had made people “vulnerable to racial discrimination and intolerance”.
Following a two-week trip visiting victims of race hate crimes in the UK, she criticised the Government’s adoption of “sweeping austerity measures” since 2010, which “disproportionately” affected ethnic minorities.
She also condemned the “hostile environment” which developed while Theresa May was Home Secretary.
“The structural socioeconomic exclusion of racial and ethnic minority communities in the United Kingdom is striking,” Ms Achiume said at a news conference.
“The harsh reality is that race, ethnicity, religion, gender, disability status and related categories all continue to determine the life chances and well-being of people in Britain in ways that are unacceptable and in many cases unlawful.
“Austerity measures have been disproportionately detrimental to racial and ethnic minority communities. Unsurprisingly, austerity has had especially pronounced intersectional consequences, making women of colour the worst affected.”
She also said the outlook for young black boys in the UK “remains grim and has actually worsened”.
Before arriving in the UK, Ms Achiume said she wanted to look into the role the EU referendum may have played in exacerbating “structural forms of discrimination and exclusion in Britain”.
“I think the environment leading up to the referendum, during the referendum and after the referendum has made racial ethnicities more vulnerable to racial discrimination and intolerance,” she said.
However, the UN inspector did praise Mrs May’s 2016 racial disparity audit, which she called a “remarkable step in transforming racial equality into reality”. She said it was “worthy of emulation by governments all over the world”.
The audit looked into how people of different ethnicities were treated across public services and assessed inequalities between different groups.
Ms Achiume also called for aspects of the 2014 and 2016 Immigration Act to be repealed.
She said: “The hostile environment will remain in place for as long as the legal and policy frameworks rooted in 2014 and 2016 Immigration Acts remain in place.
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“The UK has much to do in the arena of addressing structural and institutional forms of racial discrimination and inequality.”
She will present her findings in a report in June next year.