A British teenager was on Friday sentenced to more than 11 years in prison for videos promoting racist violence that have been linked to two mass killings in the United States.

Jailing him, Judge Patrick Field called Daniel Harris, 19, "highly dangerous" and a "propagandist for an extremist right-wing ideology".

"You were in close touch with other right-wing extremists online and there can be little doubt that you shared ideas between you," Field told Harris.

Harris was found guilty in December of five counts of encouraging terrorism and one count of possession of material for terrorist purposes for trying to make a gun with a 3D printer.

The court heard that the teenager from Derbyshire in central England posted videos online over a period of more than a year, from the age of 17.

His videos were shared by self-declared white supremacist Payton Gendron, who murdered 10 black people in Buffalo, New York in May 2022.

Police said that Harris's videos "were commented on and referenced seven times" by Gendron.

The judge at Manchester Crown Court in northern England sentenced Harris to 11.5 years with a further three years under supervised probation.

Prosecutors said a link was also found between Harris's videos and Anderson Lee Aldrich, the only suspect in a shooting in a gay nightclub in the US city of Colorado Springs in November 2022.

Police said that the suspect used one of Harris's videos on his website.

The court was told one of his videos, titled How to Achieve Victory, called for "total extermination of sub-humans once and for all".

Another video paid homage to the white supremacist murderer of British MP Jo Cox in 2016.

Harris was arrested by counter-terrorism police at his home in the small town of Glossop in May last year, two days after the attack at a supermarket in Buffalo.

Counter-Terrorism Policing detective inspector Chris Brett said in a statement following the sentencing that "Harris presents as an unassuming, quiet young man, but scratch the surface and it's a more sinister picture".

He said that attempts were made to engage with Harris through the government-led Prevent programme aimed at stopping vulnerable people becoming terrorists, but he continued to post extremist material.

"Harris was ultimately deemed not to have been groomed, rather his provocative words and inflammatory films were potentially radicalising others," Brett said.

The officer warned that "anyone who downloads, shares or creates extreme content online risks being arrested under terrorism legislation".

"And don't think you can hide behind usernames, avatars and other technical blockers, as we have teams of highly-skilled digital investigators with a track record for getting to the source."

Harris had previous convictions including for damaging a local memorial to George Floyd, a black man who died under the knee of a white police officer in the US in 2020 in a killing that sparked nationwide protests.