In a video posted to YouTube on Wednesday, Proud Boys founder Gavin McInnes publicly claimed to have quit the far-right group.

The move came two days after the Guardian exclusively revealed that the FBI had categorized the Proud Boys as “an extremist group with ties to white nationalism”, in a briefing to Washington state law enforcement.

In a sometimes rambling video, McInnes referenced the Guardian story and the prosecution of seven group members over a street brawl in New York city in October, as he offered reasons for resigning from the group.

“As of today … I am officially disassociating myself from the Proud Boys,” he began.

Referencing the New York group as the “NYC Nine”, McInnes said: “I am told by my legal team and law enforcement that this gesture could help alleviate their sentencing.”

He added: “Fine, at the very least this will show jurors they are not dealing with a gang and there is no head of operations.”

McInnes has previously described the Proud Boys as a gang.

He then said: “We are not an extremist group and we do not have ties with white nationalists”, pushing back on a description that Clark county officer commander Michael McCabe had attributed to the FBI.

However, the content and timing of the briefing in which McCabe said the FBI had offered this description was confirmed to Oregon Public Broadcasting on Monday by Clark county prosecuting attorney Tony Golik.

McInnes said: “Not one reporter talking about this ever spoke to the FBI.”

In the Guardian report, the FBI did not directly address the designation or the briefing in response to specific email questions. But it did say that while “the FBI does not and will not police ideology”, the agency “regularly assesses intelligence regarding possible threats and works closely to share that information with our federal, state and local law enforcement partners”.

Regarding white nationalists, McInnes said “such people don’t exist”. He also attacked the Southern Poverty Law Center, which has designated the Proud Boys as an extremist group; repeatedly blamed “lazy journalism” for the prosecution of members; and asked supporters to donate towards the legal defence of the Proud Boys in New York.

His recorded exhortations to violence, he said, had been taken out of context.

At times, McInnes appeared to contradict his promise to quit. He repeatedly described the group as “we”, throughout a lengthy defence of its actions, said “this is 100% a legal gesture, and it is 100% about alleviating sentencing”, and also called his actions a “stepping down gesture, in quotation marks”.

McInnes – who co-founded Vice Media, which he left in 2009 – founded the “western chauvinist” and “pro Trump” Proud Boys in 2016. Members have been involved in repeated incidents of street violence around the US, including a declared riot in Portland, Oregon.

Between August and October, McInnes and the Proud Boys were banned from major social media platforms including Facebook and Twitter. Earlier this month they were banned from payment service PayPal.

Branches have been established in Israel, Australia and Canada. On Tuesday, the former commander of Australia’s Border Force said the government should refuse McInnes a visa for a planned tour, telling Fairfax media McInnes “presented a greater threat to community safety than some Muslim preachers who have recently been denied visas on character grounds”.

In his video, having distanced himself from the group by saying “I was never the leader, only the founder”, McInnes concluded: “I still see it as the greatest fraternal organization in the world”.

Following McInnes’s announcement, former Breitbart writer and “alt right” popularizer Milo Yiannopoulos also said he was resigning from the group. In a blogpost, Yiannopoulos said he had been “instructed by my lawyers today to add my voice to that of Gavin McInnes, the founder of the fraternal men’s organization, and announce that I am publicly dissociating myself with the club”.

Like McInnes, Yiannopoulos blamed the media for spreading what he called a “great white supremacy hoax” until it “reached federal law enforcement agencies”.