Thousands of Black Lives Matter protesters have been pouring into the US capital in what is anticipated could be Washington’s biggest ever rally.

On the 12th day of demonstrations in America sparked by George Floyd’s death, crowds are on Sunday morning (Australian time) swelling at important sites including the Capitol, the Lincoln Memorial and Lafayette Park.

It comes amid a wave of solidarity protests around the world including the UK, Europe and Australia where thousands of people have taken to the streets despite health warnings from politicians about spreading the coronavirus.

Hundreds also came out to demonstrate in Tokyo and Seoul.

• Related: Why Australians ignored the warnings to flock to Black Lives Matter protests

Washington DC police are preparing for what the police chief said “may be one of the largest (rallies) we’ve ever had in the city”.

Six buses unloaded several hundred uniformed military personnel, most wearing body armour and carrying shields, at the White House grounds early on Saturday.

Military Humvees were parked on tree-lined city streets.

People from many backgrounds walk along the recently renamed Black Lives Matter Plaza near the White House. Photo: Getty

Police are out in smaller numbers around the marchers, wearing patrol uniforms rather than body armour and helmets.

Officers appear in a more relaxed posture after earlier drawing criticism for firing smoke grenades and chemical irritant “pepper balls” before charging into peaceful protesters near the White House on Tuesday (local time).

The latest protests come as authorities in the upstate New York city of Buffalo charged two police officers with assault after they were filmed pushing an elderly man to the ground.

Two Buffalo police officers have been charged with assault after a video showed them shoving a 75-year-old protester in recent demonstrations over the death of George Floyd.

https://twitter.com/shaunking/status/1269401231711252480

Robert McCabe, 32, and Aaron Torgalski, 39, who both surrendered on Saturday morning, pleaded not guilty to second-degree assault. They were released without bail.

The duo “crossed a line” when they shoved the man down hard enough for him to fall backward, hit his head and bleed profusely, Erie County District Attorney John Flynn said, calling the victim “a harmless 75-year-old man.”

If convicted of the felony assault charge, they face up to seven years in prison.

The crowd in Philly is…unfathomable? I can’t even guess. Unbelievable. pic.twitter.com/02ZIcyTXW5

— Bradford Pearson (@BradfordPearson) June 6, 2020

McCabe’s lawyer, Tom Burton, said after the arraignment that prosecutors didn’t have any grounds to bring felony charges. He said his client is a decorated military veteran with a clean record as a police officer.

“Nobody started out their day intending to hurt this fellow,” Burton said. He added that if the victim had followed commands to back off, “none of this would have happened.”

Global movement

America’s unrest has spurred people around the world to stand up against racism in the face of authorities enforcing coronavirus restrictions.

Protests in the UK took place in London, Manchester, Cardiff, Leicester and Sheffield despite officials advising against the mass gatherings.

Protestors scuffle with Police officers in riot gear near Downing Street, London. Photo: Getty

After a largely peaceful Saturday, small numbers of protesters near Prime Minister Boris Johnson’s Downing Street residence threw bottles at police, and mounted officers charged at protesters to push them back.

One officer required hospital treatment after falling from her horse, police said.

More than a thousand protesters marched past the US Embassy on the south bank of the River Thames.

In France, some 23,000 people demonstrated nationwide, 5500 of them in Paris, French media reported, citing the Interior Ministry.

Paris authorities banned demonstrations planned outside the US Embassy and on the lawns near the Eiffel Tower.

Police and protesters face off on Champ de Mars in front of the Eiffel Tower. Photo: Getty

However, several hundred protesters, some holding “Black Lives Matters” signs, gathered on Place de la Concorde, close to the embassy.

Police had installed a long barrier across the square to prevent access to the embassy, which is also close to the Elysee presidential palace.

Police in the German city of Hamburg used pepper spray on protesters and said they were ready to deploy water cannons. One officer was injured, they added.

Several hundred “hooded and aggressive people” had put officers under pressure in the city centre, police said, tweeting: “Attacks on police officers are unacceptable!”

In Berlin, demonstrators filled the central Alexanderplatz square, while there was also a protest in Warsaw.

Washington demonstration

On the steps of the Lincoln Memorial, 27-year-old construction worker Delonno Carroll said he had come out to demonstrate because he “simply cannot” sit and watch from home.

“Our voices need to be heard,” Mr Carroll said.

“No longer can we have a man call out for his mum on the streets and have to go through what George Floyd did.”

Demonstrators at the Lincoln Memorial in Washington. Photo: Getty

Floyd, 46, died on May 25 in Minneapolis after a police officer knelt on his neck for nearly nine minutes.

The killing has triggered protests against racism and police brutality in cities and smaller communities nationwide, as well as demonstrations by supporters around the world.

By noon (local time) about 3000 demonstrators had gathered at the Lincoln Memorial and about the same number were near the White House, DC police reported.

Another group of protesters was in front of the US Capitol.

Supporters kneel near the White House. Photo: Getty

Some passing motorists honked their horns in support, and some city residents came out on the street to hand out water and snacks to offer protesters relief from the sweltering heat.

Hundreds of demonstrators who marched past the George Washington University Hospital chanted “Hands up, Don’t shoot!”, “We March for hope, not for hate,” and “I can’t breathe!”

That last chant echoed protests from New York in 2014, when Eric Garner died in police custody after an officer used a banned chokehold on him.

Crowds at the newly named Black Lives Plaza across from Lafayette Park. Photo: Getty

-with AAP