White supremacists and anarchists pose major US domestic terror threats and could spark violence at events related to the November 3 election, the Department of Homeland Security said Tuesday.

A long-awaited report on security threats to the country said white supremacists were responsible for 39 of the 48 deaths attributed to domestic violent extremists in 2018-2019, with other categories of extremists to blame for the rest.

But DHS said that in the past year, anti-government, anti-authority anarchists -- indicating those who have carried out protests against police and racism -- pose a newer threat.

Since September 2019, Acting DHS Secretary Chad Wolf said in a preface to the report, "we began to see a new, alarming trend of exploitation of lawful protests causing violence, death, and destruction in American communities" by such groups.

He cited injuries to 300 law enforcement personnel during the protests that "significantly threatens the Homeland by undermining officer and public safety -- as well as our values and way of life."

Reportedly delayed for months by internal administration politics over how domestic extremists would be portrayed, the report eschews "leftist" and "rightist" labels.

Since early this year, President Donald Trump, Attorney General Bill Barr and Wolf have singled out "radical anarchist" and "left-wing" groups as a deep threat to the country, citing violent protests in several cities where dozens of police have been injured.

Trump has made the claim a key part of his reelection pitch to voters, while avoiding any talk of right-wing extremists including neo-Nazis and white supremacists tied to numerous deaths, including the murder of law enforcement officials.

Last week, Trump even appeared to encourage one armed and violent nationalist group, the Proud Boys, telling them to "stand by" because "somebody's got to do something" about the left.

Nevertheless, the DHS report associated multiple mass attacks and deaths to extremists on the right, but not on the left.

A number of attacks early this year, including the murders of three police officers, have been tied to nationalist extremists, not necessarily with any racial overtones, FBI director Christ Wray has said.

The report warns that some extremists "might target events related to the 2020 presidential campaigns, the election itself, election results, or the post-election period."

"Such actors could mobilize quickly to threaten or engage in violence," the report said.