"The Proud Boys" — a combative, far-right group of self-described "western chauvinists" — have been branded an "extremist group with ties to white nationalism" by the FBI, according to internal law enforcement documents, which also note they've spawned a sinister sister organization called "The Proud Boys' Girls."

The new federal designation was revealed in an internal affairs report by a sheriff’s department in Washington state, which was obtained by a watchdog group called Property of the People.

“The FBI has warned local law enforcement that the Proud Boys are actively recruiting in the Pacific Northwest and that some in the group have contributed to the escalation of violence at political rallies held on college campuses,” the report, dated July 5, states.

The Proud Boys have became known for their unapologetic misogyny, opposition to Muslims, and violent street brawls with so-called anti-fascist groups that made headlines.

While group founder Gavin McInnes — who also co-founded the now-mainstream Vice Media — did not respond to a request for comment on the FBI's move, the Proud Boys have long denied any connection to the racist elements of the alt-right, and maintain they are a fraternal group opposed to political correctness and are open to "all races, religions and sexual preferences."

The FBI said in a statement distributed by spokeswoman Kelsey Pietranton that it does not "police ideology."

"Our focus is not on membership in particular groups but on individuals who commit violence and criminal activity that constitutes a federal crime or poses a threat to national security," the FBI statement said. "When it comes to domestic terrorism, our investigations focus solely on criminal activity of individuals — regardless of group membership — which appears to be intended to intimidate or coerce the civilian population or influence the policy of the government by intimidation or coercion."

In the report, the Clark County Sheriff’s Office detailed that it had fired a deputy named Erin Willey on July 17 for failing to disclose that she was member of the Proud Boys' Girls.

"The Proud Boy (sic) Girls are believed to be an affiliate group of women who openly support the ideology of the Proud Boys," the report states. “The FBI Seattle office is unsure of how many female members are active in the Pacific Northwest.”

The Proud Boys’ Girls group, which was founded in 2016, is mentioned on the Proud Boys website and, until recently, had a dedicated Facebook page with 3,200 likes.

And the Proud Boys even admit on their site that “it may seem counterintuitive that a men-only group would have such a big female following."

That admission follows with a testimonial from purported PBG member identified on the site as Gabriela Finch who claims "Proud Boys saved my marriage."

"I was completely done with it, but he won me back and fought hard for it," said Finch, who NBC News has been trying to locate for comment.

The Southern Poverty Law Center, which tracks hate groups, said the FBI designation does not come as a surprise to them.

"Their disavowals of bigotry are belied by their actions," the SPLC states on their website. "Rank-and-file Proud Boys and leaders regularly spout white nationalist memes and maintain affiliations with known extremists."

McInnes himself has ties to the racist right, the SPLC maintains.

But the phenomenon of the Proud Boys' Girls is apparently so new there is no mention of the sorority on the SPLC's description of the Proud Boys.

"We honestly don’t know a whole lot about them," SPLC research analyst Keegan Hankes told NBC News on Tuesday.

Willey, 26, was a cadet with the Clark County Sheriff’s Office, which is headquartered in Vancouver, Washington, from 2012 to 2014 and a probationary deputy from June 2017 until she was fired in July, according to the department.

Writing in the report, Clark County Sheriff’s Commander Michael McCabe said the department had no inkling Willey was involved with the group until The Columbian newspaper in Vancouver reached out for the ex-deputy’s work history.

The department later learned the newspaper had gotten a photo of Willey wearing “Proud Boy Girls’ apparel,” most likely from a spurned boyfriend identified in the report as Graham Jorgensen.

Under questioning, Willey admitted she videotaped Jorgensen being pummeled as part of his initiation into the Proud Boys. But investigators "found no direct link to Erin actively participating — on or off-duty —in any overt forms of hate speech or discrimination, beyond wearing and selling their merchandise."

“Erin Willey comes across as a tolerant person and someone who would not promote hate speech,” the report states.

Still, Willey acknowledged that she did not disclose that she was a member of Proud Boys’ Girls when she was hired as a deputy sheriff.

"Erin either knew or should have known that any affiliation with and promotion of the group Proud Boys and Proud Boy (sic) Girls would be prohibited by the Sheriff’s Office," the report states.

Reached by telephone, Willey said, "If you have any questions about this you can talk to my attorney." She then hung up without giving the name or number of her lawyer.