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A British aristocrat who offered a reward on Facebook for the "accidental" death of a high-profile anti-Brexit campaigner has been sentenced to 12 weeks in prison.

Britain's Crown Prosecution Service said the message posted by Rhodri Philipps — who holds the title "Viscount of St. Davids" and is a member of the House of Lords — was a "hate crime."

Philipps posted the message about businesswoman and activist Gina Miller last year. It came just four days after she won a landmark court case on Britain's exit from the European Union, known as Brexit.

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The 50-year-old aristocrat wrote on Facebook: "£5,000 for the first person to 'accidentally' run over this bloody troublesome first generation immigrant."

He added: "If this is what we should expect from immigrants, send them back to their stinking jungles."

The post has since been removed.

Anti-Brexit campaigner Gina Miller arrives in court on July 10, for the trial against Rhodri Philipps, who posted Facebook messages offering a bounty on her head. Tolga Akmen / Rex Features via AP Images

Philipps would have been sentenced to eight weeks in prison but the Crown Prosecution Service, more commonly known as the CPS, asked for this to be increased because the offense was "racially aggravated."

"Where offences are motivated by hostility towards victims based on their perceived race, religion, disability, sexual orientation or transgender identity, the CPS has a duty to ask the court for a formal 'uplift' in sentencing," Kate Mulholland, London CPS reviewing lawyer, said in a statement.

She said that his "menacing comment ... was clearly racially motivated and as a result he has received a longer sentence today to reflect the hate-crime element."

Rhodri Philipps, the 4th Viscount St Davids, faces jail time for making threatening statements against anti-Brexit campaigner Gina Miller. Tolga Akmen / Rex Features via AP Images

In court earlier this week, Philipps called his message "satire" a "joke," and a "conversation piece for his Facebook friends," according to the BBC.

Miller, 52, said she found his comments "genuinely shocking" and left her "very scared for the safety of herself and her family," ITV News reported.

Philipps was actually convicted on two counts of sending a menacing public communication. The other related to a menacing message about a migrant called Arnold Sube, but that was not deemed to be racially aggravated.