The United States Congress has unanimously passed a resolution condemning neo-Nazis, the Ku Klux Klan (KKK) and other white supremacists, and urging President Donald Trump to address hate groups after last month's deadly racially-charged violence in Charlottesville, Virginia.

Tuesday's joint resolution, which describes the killing of a 32-year-old woman as a "domestic terrorist attack", calls on the Trump administration to improve data collection on hate crimes and speak out against increasingly prevalent hate groups.

Last month, hundreds of white supremacists gathered in Charlottesville under the banner "Unite the Right" over the city's planned removal of a statue of Confederate General Robert E Lee.

They clashed with the city's residents, anti-racist protesters and anti-fascists.

During the rally, a man with links to a white supremacist group rammed his car into a crowd of anti-racist protesters, killing Heather Heyer and injuring more than a dozen others.

Trump was criticised for his response to the violence and the rally, in which he asserted there were good people on "both sides" and bemoaned efforts to remove Confederate monuments as an attack on American "history and culture".

He also said that there were "very fine people" among the white supremacists attending the rally.

'No place for hate'

The House of Representatives unanimously approved the measure on Tuesday, after the Senate did so a day earlier. It now goes to Trump for his signature.

Legislators from Virginia said Congress spoke with "a unified voice" to unequivocally condemn the unrest in which Heyer was killed.

The measure recognises and offers condolences for the deaths of Heyer and two emergency responders killed in a helicopter crash while monitoring the rally, as well as 19 people injured in the violence.

"I hope this bipartisan action will help heal the wounds left in the aftermath of this tragedy and send a clear message to those that seek to divide our country that there is no place for hate and violence," House Democrat Gerry Connelly said.

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The resolution expresses support for the Charlottesville community, while "rejecting white nationalists, white supremacists, the Ku Klux Klan, neo-Nazis and other hate groups, and urging the president and the president's cabinet to use all available resources to address the threats posed by those groups".

It also calls on Attorney General Jeff Sessions to "investigate thoroughly all acts of violence, intimidation and domestic terrorism by white supremacists, white nationalists, neo-Nazis, the Ku Klux Klan, and associated groups".

Usually, such resolutions are passed as a statement of intent or a declaration that affects Congress' operations, but are not sent to the president.

The authors of the resolution, however, purposefully submitted it as a "joint resolution", which is required to be signed by Trump.

The White House has yet to comment on the resolution.

'Alarming' racism

Since Trump's election, rights groups and monitors have documented a dramatic increase in the number of hate crimes in the US.

Between the November 8 election of Trump and April, the Southern Poverty Law Center (SPLC) watchdog recorded 1,863 bias incidents. In the 10 days following Trump's election, the SPLC documented an average of 87 hate incidents a day, which was five times the daily average recorded by the FBI in 2015.

Last month, the UN issued a rare warning over what it called "alarming" racism in the US.

"We are alarmed by the racist demonstrations, with overtly racist slogans, chants and salutes by white nationalists, neo-Nazis, and the Ku Klux Klan, promoting white supremacy and inciting racial discrimination and hatred," the chair of the UN Committee on the Elimination of Racial Discrimination (CERD) said.

The human rights experts called on the US and its leadership to "unequivocally and unconditionally" condemn racist speech and crimes, warning that a failure to do so could fuel further violent incidents.