White Lives Matter will be officially declared a "hate group" by a US civil rights organisation.

The group, inspired by the Black Lives Matter movement which was launched in the wake of police killings of unarmed young black men, will be classified as a hate group in 2017 by the Southern Poverty Law Center (SPLC), a long-time US civil rights organisation that tracks extremist groups.

The SPLC calls the group a "racist" response to Black Lives Matter.

"Its main activists, to put it plainly, are unvarnished white supremacists" with long histories in racist movement from the "fever swamps of the radical right", SPLC's Sarah Viets writes in a blog post.

Its message has reportedly been co-opted by members of the Aryan Strikeforce, a skinhead group, and the National Socialist Movement, America's largest neo-Nazi group.

The group is dedicated to "the promotion of the white race" and claims to have representatives in several states, which the SPLC is investigating, said the law centre's website. The SPLC will release a full list of any chapters in February 2017.

The SPLC defines hate groups as "those that vilify entire groups of people based on immutable characteristics such as race or ethnicity". That's a definition that mirrors one the federal government used to prosecute hate crimes.

"This is exactly what White Lives Matter has been doing," SPLC senior fellow Mark Potok told ABC News. "When you have a group of people saying that an entire group of human beings are less — that all black people are criminals and all Muslims are mad bombers — that's a hate group."

The SPLC has also been called on to declare the Black Lives Matter movement a hate group, but it's a very different type of association, according to the SPLC.

"Its leadership and majority of members have never suggested all white people are evil or that all police officers should be killed or hurt," said Potok.

"They're a civil rights organization," he added. "White Lives Matter is completely different. They're quite literally neo-Nazis who think white people are the cream of the earth and that marginalized groups — such as black people, Muslims, and gay people — are their enemies."

Pressure mounted on the SPLC to declare Black Lives Matter a terror group after the ambush shootings of eight police officers in Dallas and Baton Rouge, just days after Black Lives Matter national demonstrations to protest the deaths of black men Alton Sterling and Philando Castile by police.

Thousands signed Change.org petitions calling on the SPLC to make Black Lives Matter a hate group.

That won't be the case — though black groups, such as the New Black Panther Party, have made the list.

"There's no doubt that some protesters who claim the mantle of Black Lives Matter have said offensive things," SPLC president Richard Cohen conceded in a blog post.

"But before we condemn the entire movement for the words of a few, we should ask ourselves whether we would also condemn the entire Republican Party for the racist words of its nominee — or for the racist rhetoric of many other politicians in the party over the course of years.

"Black Lives Matter is not a hate group. But the perception that it is racist illustrates the problem. Our society as a whole still does not accept that racial injustice remains pervasive."