A leader of the far-right Proud Boys has been sentenced to 17 years in prison, one of the longest sentences yet handed out over the US Capitol riot.

Prosecutors said US Army veteran Joe Biggs, 38, was an "instigator" of the storming of Congress on 6 January 2021.

The former Infowars correspondent was convicted of seditious conspiracy and other charges in May.

In court, Biggs pleaded for leniency and expressed remorse for his actions.

The sentence, handed down by US District Judge Timothy Kelly, is below both federal sentencing guidelines and the 33 years sought by prosecutors.

Another Proud Boys member, Zachary Rehl, was sentenced on Thursday to 15 years, also on a charge of seditious conspiracy.

Rehl, a former US Marine and leader of the Philadelphia branch of the Proud Boys, was seen on video spraying a chemical irritant at officers outside the Capitol during the riot.

Biggs was convicted of a slew of charges in May, including seditious conspiracy, conspiracy to use, intimidation or threats to prevent officials from discharging their duties and interference with law enforcement during civil disorder.

In a sentencing memo, prosecutors said that Biggs - a veteran of the war in Iraq and former correspondent for conspiracy website Infowars - "employed his military experience to direct and control large groups of men under his command" to lead a "revolt against the government".

"Biggs viewed himself and his movement as a second American revolution where he and the other 'patriots' would retake the government by force," the memo said.

In court, a tearful Biggs apologised for his actions and said he was "seduced" by the crowd on the day of the riot.

"I just moved forward. My curiosity got the better of me," he added. "I'm not a terrorist. I don't have hate in my heart."

"I know that I have to be punished, and I understand," Biggs said.

As he sentenced Biggs, Judge Kelly said he was "not trying to minimise the violence" but that the 6 January riot paled in comparison to other mass casualty events. He also said that a stricter sentence may have created sentencing disparities with other convicted rioters.

Biggs went to trial alongside four other Proud Boys members including former chair Enrique Tarrio, whose sentencing was abruptly postponed on Wednesday. His sentencing is now scheduled to take place next week. Prosecutors are seeking a 33-year sentence.

The Proud Boys involved in the case have said they plan to appeal against the conviction.

In court, federal prosecutor Jason McCullough said the crimes are "very serious" and that a stiff sentence would send a message ahead of next year's presidential election.

"There is a reason why we will hold our collective breaths as we approach future elections. … They pushed this to the edge of a constitutional crisis," he said.

Prosecutors used text messages, social media posts and videos to show that the Proud Boys were involved in a co-ordinated effort to stop the certification of the 2020 election at the Capitol.

As of 6 August, over 1,100 people had been arrested on charges related to the riot, resulting in over 630 guilty pleas and 110 convictions.

Another prominent participant in the riot, Oath Keepers founder Stewart Rhodes, was sentenced to 18 years in prison in May. (BBC)

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