The UK has announced fresh sanctions against Russia after the appeal of a Jewish British-Russian dissident facing 25 years in jail for opposing Vladimir Putin’s invasion of Ukraine was rejected. 

Vladimir Kara-Murza Jr was sentenced to 25 years in prison in April after he had been convicted of high treason by a Moscow court over speeches he had made about the Ukraine war. 

The 41-year-old was one of a small number of prominent opposition figures who stayed in Russia after Putin sent tens of thousands of troops into Ukraine in February last year. 

Kara-Murza has made several speeches about the war, including one to the Arizona House of Representatives in which he said Putin was bombing Ukrainian homes, hospitals and schools.

He also said Russia was run by "a regime of murderers" in an interview with CNN.

The Jewish dissident has also over the years pleaded in the United States and Europe for the adoption of individual sanctions against Russian officials.

Vladimir Kara-Murza

Russian opposition activist Vladimir Kara-Murza is escorted for a hearing (Photo: Getty)

Kara-Murza, whose mother is Jewish, was arrested two months after the war began, accused of spreading false information about the armed forces and declared a "foreign agent". 

During his trial, he compared the wording of the charges against him with that used by Soviet dictator Josef Stalin's secret police in the 1930s, when Kara-Murza's own grandfather was sent to a Gulag prison camp in Russia's far east.

The RIA state news agency reported on Monday that an appeal against his sentence had been rejected. 

UK Prime Minister Rishi Sunak labelled the rejection of the appeal by judges in Moscow as "desperate and unfounded", adding on Twitter: "He should be released immediately. The United Kingdom stands with him and his family."

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Former foreign secretary and new home secretary James Cleverly (Photo: Getty)

The UK Government announced that it had sanctioned six individuals, including two Moscow city court judges, for their involvement in the conviction of Kara-Murza.

Foreign Secretary James Cleverly said: "The rejection of Vladimir Kara-Murza's appeal following his sentencing on bogus charges highlights the depravity of the Russian regime and their complete disregard for human rights and freedom of expression.

"Today we've sanctioned six people connected with his case, sending a clear message that the UK will not stand for this treatment of one of its citizens."