​U.S. President Donald Trump denounced neo-Nazis and the Ku Klux Klan as criminals and thugs on Monday, bowing to mounting political pressure to condemn such groups explicitly after a white nationalist rally turned deadly in Virginia.

Trump had been assailed from across the political spectrum for failing to respond more forcefully to Saturday's violence in Charlottesville, in which a woman was killed when a man crashed his car into a group of counter-protesters.

WARNING | graphic content | Car plows into Virginia crowd1:37

Critics said Trump waited too long to address the bloodshed and slammed him for initially saying that "many sides" were involved, instead of singling out the white supremacists widely seen as sparking the melee.

"Racism is evil and those who cause violence in its name are criminals and thugs, including the KKK, neo-Nazis, white supremacists and other hate groups that are repugnant to everything we hold dear as Americans," the president said in a statement to reporters at the White House on Monday. "We condemn in the strongest possible terms this egregious display of hatred, bigotry and violence."

'Justice will be delivered'

A 20-year-old man said to have harboured Nazi sympathies as a teenager was facing charges that he plowed his car into protesters opposing the white nationalists, killing Heather Heyer and injuring at least 19 people. 

The accused, James Alex Fields, was denied bail at an initial court hearing on Monday.

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Fields was photographed before the attack attending the white nationalist rally, holding a shield adorned with the symbol of Vanguard America, a white supremacist organization. (Eze Amos/Reuters)

Trump said anyone who engaged in criminal behaviour during the rally would be held accountable.

"Justice will be delivered," the Republican president said.

'It took 48 hours'

"I wish that he would have said those same words on Saturday," responded Democratic Sen. Mark Warner of Virginia on MSNBC. "I'm disappointed it took him a couple of days."

Al Sharpton, one of the country's best-known black civil rights activists, echoed that.

"It took 48 hours.... It was clearly a statement based on the pressure that he had been given over the weekend," he said on MSNBC.

Trump lashed out at his critics again later on Monday on Twitter: "Made additional remarks on Charlottesville and realize 
once again that the #Fake News Media will never be satisfied ... truly bad people!"

In a strong rebuke to Trump earlier on Monday, the chief executive of Merck & Co. Inc., one of the world's largest pharmaceutical companies, resigned from a business panel led by the president.

CEO Kenneth Frazier, who is black, said he was taking a stand against intolerance and extremism.

Trump attacks CEO

Trump hit back, making no reference to Frazier's reasons for quitting the panel and instead revisiting a longstanding gripe about expensive medicines. Frazier would now have more time to focus on lowering "ripoff" drug prices, Trump tweeted.

Several executives from top U.S. companies have previously stepped down from presidential advisory councils in protest at Trump policies.

Trump calls out KKK, hate groups, condemns hatred, bigotry and violence in Charlottesville4:14

The jarring images of violence from Charlottesville and the heated public debate over racism resonated around the world, particularly in Europe where leaders are contending with a wave of xenophobia.
 
German Chancellor Angela Merkel told local broadcaster Phoenix on Monday that clear and forceful action must be taken to counter right-wing extremism, and that "we have quite a lot to do at home ourselves."
 
About 130 people demonstrated outside the U.S. Embassy in London, some with placards reading "Fascism is not to be 
debated, it is to be smashed," and "I am an ashamed American."

In assailing the president for his earlier comments on the violence in Charlottesville, critics noted that right-wing extremists have been a loyal segment of Trump's political base.

'Words of comfort'

The mother of the woman killed on Saturday welcomed Trump's latest comments.

Confederate Monument Protest

A makeshift memorial honours Heather Heyer, who was run down by a car while protesting in Charlottesville, Va., on Sunday. (Steve Helber/Associated Press)

In a statement cited by NBC News, Susan Bro thanked Trump for what she called "those words of comfort and for denouncing those who promote violence and hatred."

Heyer, 32, died after a car slammed into a crowd of anti-racism activists, capping a day of street brawls between the two sides.

'Infatuated with the Nazis'

Fields appeared in a Charlottesville court on Monday by video link from the jail where he is being held on a second-degree murder charge, three counts of malicious wounding and a single count of leaving the scene of a fatal accident.

His next court date was set for Aug. 25.

The U.S. Justice Department is carrying out its own federal investigation of the incident as a hate crime.

Derek Weimer, a history teacher at Fields's high school in Kentucky, told Cincinnati television station WCPO-TV he recalled Fields harbouring "some very radical views on race" as a student and was "very infatuated with the Nazis, with Adolf Hitler."

Accused of beating his mother

Records from 911 calls show Fields was previously accused of beating his mother and threatening her with a knife.

'It was the most terrifying thing I've ever seen.' - Robert Armengol, car attack eyewitness

The records from the Florence Police Department in Kentucky show the man's mother had called police in 2011. Records show Fields's mother, Samantha Bloom, told police he stood behind her wielding a 12-inch knife. Bloom is disabled and uses a wheelchair. 
 
In another incident in 2010, Bloom said that Fields smacked her in the head and locked her in the bathroom after she told him to stop playing video games. Bloom told officers Fields was on medication to control his temper.

'Nazis go home!'

A small group of people clashed outside the courthouse after the hearing, with two men blaming those who protested against the white nationalist rally for starting the trouble.

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White nationalist leader Matthew Heimbach screams at the media outside Charlottesville General Courthouse in defence of James Alex Fields Jr. (Justin Ide/Reuters)

"The police department did not do anything to protect us," said Matthew Heimbach, one of the men. "Radical leftists are the ones that brought the violence."

A woman yelled "Nazis go home!" at Heimbach until police ushered her away.

The Southern Poverty Law Centre said Heimbach is considered the face of a new generation of white nationalists.

Fight over statue removal

The weekend disturbances began when white nationalists converged to protest against plans to remove a statue of Confederate Gen. Robert E. Lee, the commander of rebel forces during the U.S. Civil War.

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Protesters chant slogans against white nationalism in Times Square in New York City on Monday. (Joe Penney/Reuters)

"It was the most terrifying thing I've ever seen," said Robert Armengol, who teaches anthropology at the University of Virginia. 

Armengol was covering the scene for a podcast he makes with his students when a grey car approached the crowd, he told CBC News. 

It approached slowly, he said. "But when it came within a few feet of the crowd it accelerated. It sent bodies, shoes, personal belongings flying in every direction and everyone started running for their lives."

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Rescue workers assist a victim who was injured when a car drove through a group of counter-protesters at the 'Unite the Right' rally in Charlottesville, Va., on Satuday. (Joshua Roberts/Reuters)

With files from CBC News and The Associated Press