"We have serious concerns about impunity and the failure to address racial disparities in the criminal justice system, deaths in police custody, 'joint enterprise' convictions and the dehumanizing nature of the stop and (strip) search" police tactic, the UN Working Group of Experts on People of African Descent said following an official visit to Britain.
Public spending cuts have exacerbated racial discrimination and intolerance, the UN group reported.
The five-member group is mandated by the UN Human Rights Council to report to the UN's top rights body. The experts are unpaid and do not speak for the UN.
The group said it had documented the "trauma" felt by people of African descent who were suffering racial discrimination and injustice in Britain.
"A decade of austerity measures in the UK had exacerbated racism, racial discrimination and other intolerance people of African descent encounter, which had an adverse impact on their fundamental rights," they found.
They said people of African descent felt public institutions and the private sector both perpetuated racial hierarchies.
"Racialized acts targeting people of African descent have remained steadfast, and the experience is similar across different parts of the UK," the experts said, after visiting London, Birmingham, Manchester and Bristol.
"They are victimized and have no assurance of effective redress from authorities or the justice system."
- Windrush scandal -
In October, a report by a top UK lawyer and the University of Manchester said it found evidence of "institutional racism" in the justice system in England and Wales, particularly in the treatment of black and Asian defendants.
The UN experts welcomed "emerging efforts towards reparation for the legacies of the trade and trafficking in enslaved Africans".
They encouraged the British government to do more to ensure the "rehabilitation, restoration and reconciliation of the state with its people."
In what became known as the Windrush scandal, it was revealed in 2017 that thousands of Britons of Caribbean origin, who arrived legally between 1948 and the early 1970s without needing documentation, had been wrongly caught up in new hardline policies targeting illegal immigrants.
Some were detained or deported.
On Thursday, British media reported that interior minister Suella Braverman had scrapped some reforms the government had promised to introduce in order to address the Windrush scandal.
Ugandan expert Catherine Namakula, who chairs the UN working group, called for accessible, independent and effective complaint mechanisms to address racism.
"Ensuring police accountability, fair trial guarantees for all persons, and redress to all persons affected by the Windrush scandal are imperative," she said.
"Austerity to the peril of fundamental rights is a costly undertaking for the UK," she added.
The group will present its findings and recommendations to the Human Rights Council in September.