US President Donald Trump’s condemnation of hate groups has disappointed and angered some white nationalists who had supported him.

Mr Trump initially blamed “many sides” after clashes in Charlottesville, Virginia, where a participant in a white nationalist rally rammed his car into a crowd of counter-protesters on Saturday, killing a demonstrator and injuring dozens of others.

Under immense bipartisan pressure to issue a stronger statement, Mr Trump explicitly denounced the Ku Klux Klan, white supremacists and neo-Nazis as “repugnant to everything we hold dear as Americans” on Monday and said “justice will be delivered” to those responsible.

Reading from a prepared text, Mr Trump said: “Those who spread violence in the name of bigotry strike at the very core of America.”

White nationalist Richard Spencer told reporters at a news conference he thought Mr Trump should have criticised state and local authorities for their handling of security at the Charlottesville rally.

“The statement sounds like we might want to all bring out an acoustic guitar and sing ‘Kum ba yah’. It’s just vapid nonsense,” said Mr Spencer, who popularised the term “alt-right” to describe the fringe movement mixing white supremacy, white nationalism, anti-Semitism and anti-immigration populism.

Occidental Dissent, a white nationalist website, posted a statement saying whites had been “deserted by their president”.

“He has sided with a group of people who attack us on sight and attempt to kill us and for that the Alt-Right can no longer support him. What Donald Trump has done today is an unforgivable betrayal of his supporters,” the message said.

Mr Trump was criticised during the presidential campaign for failing to immediately reject the endorsement of former Ku Klux Klan leader David Duke. On Monday, Mr Duke posted a video mildly criticising Mr Trump’s remarks.

“President Trump, please, for God’s sakes, don’t feel like you’ve got to say these things. It’s not going to do you any good,” he said.

Mr Duke, who participated in the rally, reserved his bile for the “fake news media” covering the events in Charlottesville as he addressed Mr Trump.

“I understand that you’re under a great amount of pressure,” he said. “The problem is you’re under siege. You know these people. They want your scalp. They want to crucify you.”

White nationalist Richard Spencer gives remarks after a white nationalist rally was declared an unlawful assemblyWhite nationalist Richard Spencer gives remarks after a white nationalist rally was declared an unlawful assembly (Shaban Athuman/AP)

The publisher of The Daily Stormer, a neo-Nazi website, praised Mr Trump’s initial reaction to the Charlottesville violence.

“Nothing specific against us,” Andrew Anglin wrote. “No condemnation at all. When asked to condemn, he just walked out of the room. Really, really good. God bless him.”

Mr Anglin dismissed Mr Trump’s second statement as “childish nonsense”.

“I’m not especially bothered by it,” he said. “If he actually believed that nonsense, or was planning on implementing it as policy, he would have said it before being bullied into it by the international thought police.”