Joshua, one of Britain’s highest-profile sportsmen, joined a march through the streets of his home town of Watford before gathering in a park where he recited a poem written by a friend, Reuters reported.

“The virus has been declared a pandemic,” Joshua said. “This is out of control. And I’m not talking about COVID-19. The virus I’m talking about is called racism.”

Marches and protests have been held all over the world in response to the killing of unarmed black man George Floyd by a police officer in the US on May 25. Four officers involved have since been charged over the death.

The 30-year-old Joshua, whose world heavyweight title defense against Bulgarian Kubrat Pulev scheduled for this month at Tottenham Hotspur’s stadium was postponed because of the COVID-19 pandemic, was dressed in all black for the event.

“We can no longer sit back and remain silent on these senseless, unlawful killings and sly racism on another human being – based on what? Only their skin color,” the IBF, WBA, and WBO world champion, who was using crutches and wearing a knee brace, after injuring his knee during training this week, added.

“We need to speak out in peaceful demonstrations – just like today, so well done Watford.

“We must not use a demonstration for selfish motives and turn it into rioting and looting.”

A spokesman for Joshua said his knee injury would be further checked by doctors, but “there is no immediate concern.”

The Black Lives Matters protests went on in London despite Health Minister Matt Hancock urging people not to attend large gatherings because of the pandemic.

The Metropolitan Police also said on Friday that the protests could be unlawful because they would break social-distancing advice.

Crystal Palace soccer player Andros Townsend took to Twitter to question why the authorities were trying to stop the marches.

“I find it funny how people in power are using COVID 19 to try and stop the #BlackLivesMatter protests in the UK… where was this same energy when there were thousands congregating around parks/beaches? Don’t hide behind the virus, say the real reason! #BlackLivesMatter,” he said.

With the Trump administration branding instigators of six nights of rioting as domestic terrorists, there were more confrontations between protestors and police and fresh outbreaks of looting, AFP reported.

Violent clashes erupted repeatedly in a small park next to the White House, with authorities using tear gas, pepper spray, and flash-bang grenades to disperse crowds who lit several large fires and damaged property.

Local US leaders appealed to citizens to give a constructive outlet to their rage over the death of an unarmed black man in Minneapolis, while night-time curfews were imposed in cities including Washington, Los Angeles, and Houston.

One closely watched protest was outside the state capitol in Minneapolis’ twin city of St. Paul, where several thousand people gathered before marching down a highway.

Hundreds of police and National Guard troops were deployed ahead of the protest.

There were other large-scale protests Sunday night, including in New York and Miami.

Washington, D.C.’s mayor ordered a curfew from 11:00 p.m. until 6:00 a.m., as a report in the New York Times said that President Donald Trump had been rushed by Secret Service agents into an underground bunker at the White House on Friday night during an earlier protest.

In Louisville, Kentucky, CBS affiliate WLKY-TV reported the local police chief as saying law enforcement shot and killed a man early Monday morning as they broke up a crowd.

Officials in L.A. – a city scarred by the 1992 riots over the police beating of Rodney King, an African-American man – imposed a curfew from 4:00 p.m. Sunday until dawn.

The shocking death last Monday of an unarmed black man, George Floyd, at the hands of police in Minneapolis ignited the nationwide wave of outrage over law enforcement’s repeated use of lethal force against unarmed African-Americans.

Floyd stopped breathing after Minneapolis police officer Derek Chauvin knelt on his neck for nearly nine minutes.

Chauvin has been charged with third-degree murder and is due to make his first appearance in court on Monday.

Late Sunday, as many were being arrested for curfew violations in Minneapolis, authorities moved Chauvin to another location from the Hennepin County Jail for his own safety, according to Minnesota’s corrections commissioner.

Three other officers with him at the arrest have been fired but for now face no charges.

Governor Tim Walz has mobilized all of Minnesota’s National Guard troops – the state guard’s biggest mobilization ever – to help restore order and extended a curfew for a third night Sunday.

The Department of Defense said that around 5,000 National Guard troops had been mobilized in 15 states as well as the capital, Washington, with another 2,000 on standby.

The widespread resort to uniformed National Guard units is rare, and evoked disturbing memories of the rioting in US cities in 1967 and 1968 in a turbulent time of protest over racial and economic disparities.

Trump blamed the extreme left for the violence, saying he planned to designate a group known as Antifa as a terrorist organization.

Atlanta Mayor Keisha Lance Bottoms said Trump, who has often urged police to use tough tactics, was not helping matters.

“We are beyond a tipping point in this country, and his rhetoric only enflames that,” she said on CBS.

Joe Biden, Trump’s likely Democratic opponent in November’s presidential election, visited the scene of one anti-racism protest.

“We are a nation in pain right now, but we must not allow this pain to destroy us,” Biden tweeted, posting a picture of him speaking with an African-American family at the site where protesters had gathered in Delaware late Saturday.

Floyd’s death has triggered protests beyond the United States, with thousands in Montreal and London marching in solidarity on Sunday.

In Germany, England football international Jadon Sancho marked one of his three goals for Borussia Dortmund against Paderborn by lifting his jersey to reveal a T-shirt bearing the words “Justice for George Floyd.”