The organiser of a far-right rally in Charlottesville has been forced to flee from his own press conference by furious demonstrators.

Key points: Mr Trump was criticised for failing to explicitly condemn white supremacists, saying "many sides" were involved

Mr Trump was criticised for failing to explicitly condemn white supremacists, saying "many sides" were involved A White House statement later said Mr Trump's condemnation "includes white supremacists, KKK, neo-Nazi, and all extremist groups"

A White House statement later said Mr Trump's condemnation "includes white supremacists, KKK, neo-Nazi, and all extremist groups" One woman was killed and 19 others injured when a car rammed a group of protesters objecting to the "Unite the Right" rally

Jason Kessler, who civil rights groups identified as a white nationalist blogger, was speaking after the Virginia college town became a battlefield between white supremacists and anti-racist groups over the weekend.

Thirty-two-year-old Heather Heyer was killed and 19 people were injured — five critically — when 20-year-old James Alex Fields Jr allegedly ploughed a car into a crowd of people objecting to the "Unite the Right" white supremacist rally.

Heather Heyer died when Fields' car ploughed into the crowd ( Supplied )

Dozens more people were injured in the disturbances.

Mr Kessler attempted to say he condemned the violence, but was drowned out by boos, before being chased away and tackled to the ground by a female protester.

The Charlottesville disturbances have put new pressure on the US President Donald Trump, with senior Republicans urging him to take an unequivocal stand against the far-right segment of his political base.

Mr Trump said "many sides" were responsible for the violence, which Virginia's Governor blamed on Nazis and white supremacists.

On Sunday the White House issued a statement saying Mr Trump's reference to "many sides" included the Ku Klux Klan and neo-Nazi groups.

"He called for national unity and bringing all Americans together," the statement said.

But Charlottesville's Mayor, Michael Signer, said Mr Trump's condemnation did not go far enough.

"Look at the campaign he ran. Look at the intentional courting ... on the one hand, of all of these white supremacists, white nationalist groups," Mr Signer said on CNN's State of the Union.

"And then look on the other hand at the repeated failure to step up and condemn, denounce, silence, put to bed, all of those different efforts just like we saw yesterday.

"This is not hard. There are two words that need to be said over and over again — white supremacy and terrorism — [and] that is exactly what we saw on display this weekend, and we are not seeing that from the White House."

Sorry, this video has expired Donald Trump called on the US to 'come together as one'. (Photo: AP/Pablo Martinez Monsivais)

Organiser says 'absolutely' more rallies to come

Mr Kessler said supporters of the event, which was originally staged to protest the planned removal of Confederate general Robert E Lee's statue from a park, would not back down.

"Absolutely we are going to have further demonstrations in Charlottesville because our constitutional rights are being denied," he said earlier.

A group of white supremacists in military regalia were carrying guns during the protest. ( Reuters: Joshua Roberts )

On Sunday morning, before the White House statement, Ivanka Trump, the President's daughter and White House adviser, appealed on Twitter for Americans to "be one country UNITED. #Charlottesville".

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Also before the statement, US senator Cory Gardner of Colorado, who chairs the Republican Party's Senate election effort, called on the President to condemn "white supremacists" and to use the term.

"Calling out people for their acts of evil — let's do it today — white nationalist, white supremacist," Senator Gardner said on US television.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 42 seconds 42 s The moment a car hit a crowd of anti-racism protesters in Charlottesville was captured on Periscope (Image: AP/ Steve Helber)

Virginia police have not yet provided a motive for the man who rammed a car into the crowd, but US attorneys and the Federal Bureau of Investigation have opened a civil rights investigation into the crash, an FBI field office said.

Four people have been arrested, including Fields, who is being held in jail on suspicion of crashing the car.

Federal authorities were also looking into a helicopter crash on Saturday that killed two Virginia state policemen, Lieutenant H Jay Cullen and Trooper-pilot Berke MM Bates, who were helping to monitor the rally.

It was not clear what caused the helicopter to come down, although police said there was no indication of foul play being a factor.

The rally stemmed from a long debate in the US South over the Confederate battle flag and other symbols of the rebel side in the Civil War, which was fought over slavery.

The white nationalists carried makeshift riot shields and many wore helmets. ( Reuters: Joshua Roberts )

The Charlottesville violence is the latest clash between far-rightists and the president's opponents.

At his January inauguration, black-clad anti-Trump protesters in Washington smashed windows, torched cars and clashed with police, leading to more than 200 arrests.

Reuters