Hundreds of people took to the streets of London on Wednesday to protest against the death in US police custody of George Floyd, as Prime Minister Boris Johnson condemned the killing but dodged questions about whether he had raised the issue with key ally Donald Trump.

Protesters, many of them in facemasks, defied coronavirus restrictions, and held aloft signs saying "Justice for George Floyd" and "Enough is enough!" as they marched from Hyde Park to the Whitehall government district in central London.

The demonstration is the latest in the British capital since Floyd, an unarmed African-American, died last week after a police officer in Minneapolis knelt on his neck.

Protests in London over George Floyd's death
Protests have taken place in several British cities, including London, Manchester and (pictured) Liverpool. Photo: AFP / Paul ELLIS

The incident, which was captured on video by an eye-witness, has provoked global outrage, and seen the officer concerned charged with third-degree murder.

"I'm here because I believe in my rights as a black person," said one protester, Lisa Ncuka, a 26-year-old student. "This is an important movement.

"Everybody should be here fighting for equality. It's not just the US's problem. It's the whole world's problem and we need to come together and spread this awareness."

Artists paints image of George Floyd
In Manchester, England, street artist Akse has put up a mural of George Floyd, the unarmed black man who died after a US police officer knelt on his neck during an arrest. Photo: AFP / Paul ELLIS

"Star Wars" actor John Boyega, who was among the crowds, gave an emotional speech, saying the demonstrators were a "physical representation" of support for Floyd and other victims.

"We can all join together to make this a better world," he said, urging a peaceful protest.

Twenty-three people were arrested and a further 10 people fined for breaching social distancing rules in protests on Sunday in London, including outside the US embassy.

Doreen Lawrence
Doreen Lawrence, pictured here at a 2018 memorial service, campaigned for decades to get justice after the racist murder of her son Stephen in 1993. Photo: POOL / Victoria Jones

There were no immediate reports of arrests on Wednesday.

Johnson, who has been accused of racism for his depictions in newspaper columns of black Africans, and Islamophobia over comments about veiled Muslim women, condemned Floyd's killing.

"I think what happened in the United States was appalling, inexcusable," he told lawmakers in his first public comment on the case.

"We all saw it on our screens and I perfectly understand people's right to protest what took place.

Demonstrations in London
The demonstration is the latest in the British capital since Floyd was killed. Photo: AFP / Ben STANSALL

"Obviously I also believe that protests should take place in a lawful and reasonable way."

But he avoided answering questions as to whether he had raised the matter with President Trump, as Britain eyes a post-Brexit trade deal with the United States.

His comments echoed those of British police chiefs, who earlier issued a joint statement saying they were "appalled and horrified by the way George Floyd lost his life".

"Justice and accountability should follow," they said, condemning the violence and damage that has followed in cities across the United States.

But they appealed for people in Britain to "work with officers" as protests spread, just as the coronavirus lockdown is being eased.

"The right to lawful protest is a key part of any democracy, which UK police uphold and facilitate," they added.

"But coronavirus remains a deadly disease and there are still restrictions in place to prevent its spread, which include not gathering outside in groups of more than six people."

Britain has its own fraught history of racism within policing, with a landmark 1999 report finding "institutional racism" in London's Metropolitan Police force.

The report was commissioned after the racist murder of a black teenager, Stephen Lawrence, at a bus stop in south London in 1993.

The police investigation was marred by a catalogue of failures that saw no-one convicted until 2012.

Despite programmes of reform, a 2015 study by the Runnymede Trust, an educational charity which aims to promote a successful multi-ethnic Britain, found "systemic and institutional racism persists" within British policing.

"Britain is no stranger to racialised police violence," it noted.

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