The human rights organization Memorial said Thursday that Oleg Navalny, brother of the prominent political activist Alexei Navalny, is a political prisoner and called for his release from jail.
The advocacy group said in an online statement that the Navalny brothers' prosecution for embezzlement at the end of last year was "politically motivated and illegal."
"In the prosecution there is a clear political motive: to stop the public activity of Alexei and the threats that his activities create for the current government," Memorial said in the statement.
The Navalny brothers were convicted on Dec. 30 of embezzling money during business transactions with French cosmetics company Yves Rocher, accusations that Memorial has denounced as "manifestly absurd." Alexei Navalny was given a suspended sentence of three-and-a-half years while his brother was sent to prison for the same period.
Memorial, which last year declared Alexei Navalny himself a political prisoner when he was put under house arrest over the Yves Rocher case, said there was no proof of a criminal offense having been committed, and that none of the alleged victims had presented any claims in a criminal trial initiated by Russia's Investigative Committee.
Alexei Navalny, a vocal critic of President Vladimir Putin and runner-up in Moscow's 2012 mayoral elections, has been accused on four occasions by Russian authorities of fraud or embezzlement relating to his business activities, according to Memorial. His younger brother Oleg is a former Russian post office employee who is not known for political activism.