London (CNN) A far-right teenager who reportedly branded Prince Harry a "race traitor" and suggested he should be shot after his marriage to Meghan Markle has been jailed in Britain for four years and three months.

Michal Szewczuk, 19, posted extremist material including an image of the prince with a gun to his head on a blood-spattered background, the UK Press Association (PA) news agency reported.

Published months after Harry's wedding to Meghan, whose mother is African-American, the image also featured a swastika and the phrase: "See Ya Later Race Traitor."

Szewczuk was sentenced at the Old Bailey in London Tuesday, after pleading guilty to two counts of encouraging terrorism and five accounts of possessing terrorist material, the UK's Counter Terrorism Policing (CTP) unit confirmed in a statement

Among the materials in Szewczuk's possession was the White Resistance Manual -- a white supremacist handbook -- and the al Qaeda Training Manual, PA said.

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