Russian police have detained dozens of opposition supporters after a protest to mark the 50th birthday of jailed businessman Mikhail Khodorkovsky.
Police said officers detained some 40 protesters who marched along Moscow's Old Arbat Street after the official end of the sanctioned protest on June 26.
Khodorkovsky, the former head of the now dismantled Yukos oil company turned Kremlin critic, was detained in 2003.
He was found guilty of tax evasion and embezzlement in two trials in 2005 and 2010.
The charges against Khodorkovsky were widely seen as politically motivated.
He is expected to remain in prison until October 2014.
Police said officers detained some 40 protesters who marched along Moscow's Old Arbat Street after the official end of the sanctioned protest on June 26.
Khodorkovsky, the former head of the now dismantled Yukos oil company turned Kremlin critic, was detained in 2003.
He was found guilty of tax evasion and embezzlement in two trials in 2005 and 2010.
The charges against Khodorkovsky were widely seen as politically motivated.
He is expected to remain in prison until October 2014.