Clashes across US as protesters defy curfews

The crowd remained in Lafayette Square and elsewhere in the capital after curfew, despite threats by Trump to use the military to crack down on what he has called lawlessness by "hoodlums" and "thugs."

Dozens of National Guard troops lined up on the steps of the Lincoln Memorial behind black crowd-control barriers.

In New York City, thousands of chanting and cheering protesters ignored an 8pm curfew to march towards the Brooklyn Bridge as police helicopters whirred overheard.

On Hollywood Boulevard in Los Angeles, hundreds of people filled the street from curb to curb. Others gathered outside Los Angeles Police Department headquarters downtown, in some cases hugging and shaking hands with a line of officers outside.

Los Angeles was the scene of violent riots in the spring of 1992, following the acquittal of four policemen charged in the beating of black motorist Rodney King, that saw more than 60 people killed and an estimated $US1 billion ($1.4 billion) in damage.

A Reuters/Ipsos poll released on Tuesday found a majority of Americans sympathise with the protests.

The survey conducted on Monday and Tuesday found 64 per cent of American adults were "sympathetic to people who are out protesting right now", while 27 per cent said they were not and 9 per cent were unsure.

More than 55 per cent of Americans said they disapproved of Mr Trump's handling of the protests, while just one-third said they approved.

Death of a father

In Minneapolis, Roxie Washington, mother of Floyd's 6-year-old daughter, Gianna, told a news conference he was a good man. "I want everybody to know that this is what those officers took from me," she said, sobbing. "Gianna does not have a father. He will never see her grow up, graduate."

Floyd died after a white policeman pinned his neck under a knee for nearly nine minutes in Minneapolis on May 25.

The officer who knelt on Floyd, 44-year-old Derek Chauvin, has been charged with third-degree murder and second-degree manslaughter. Three other officers involved were fired but not yet charged.

The head of the US National Guard said on Tuesday 18,000 Guard members were assisting local law enforcement in 29 states.

The Pentagon said it has moved about 1600 US Army troops into the Washington, DC, region.

Trump's militaristic rhetoric and the growing role of the US armed forces has alarmed some current and former officials.

"America is not a battleground. Our fellow citizens are not the enemy," Martin Dempsey, a retired four-star general who served as chairman of the Joint Chiefs of Staff, wrote on Twitter.

Some of those who have gathered at the site of Floyd's killing have invoked the non-violent message of the late US civil rights leader Martin Luther King jnr, assassinated in 1968, as the only way forward.

"He would be truly appalled by the violence because he gave his life for this stuff," said Al Clark, 62, a black man who drove to the Minneapolis memorial with one of King's speeches blaring from his truck.

"But I can understand the frustration and anger."

AAP