Around 50 activists wearing red T-shirts with Khodorkovsky's portrait on them marched down the Old Arbat pedestrian street handing out shirts and balloons.
Suddenly from the rooftop of a building along their route, a large plastic banner wishing Khodorkovsky a happy birthday and freedom unfurled, spilling leaflets onto the street. Firecrackers went off on the roof.
Police detained about 10 of the activists, who were then driven away in police vehicles.
Demonstrations also were planned Sunday in St. Petersburg and London.
Khodorkovsky has been in prison since his arrest in 2003 on charges seen as punishment for challenging the power of Vladimir Putin, who was president at the time and is now prime minister. A second conviction late last year will keep Khodorkovsky incarcerated until 2016 unless he is granted parole.
Khodorkovsky, once Russia's richest man, has won admiration from some of his countrymen for his refusal to bend. For his supporters, he has become a symbol of the corruption and other excesses under Putin.
Many Russians, though, have little sympathy for Khodorkovsky, who was one of a small circle of politically connected businessmen who grew fabulously wealthy after taking over state companies in the 1990s.
Moscow: Police detained about 10 activists at a Moscow demonstration in support of jailed oil tycoon Mikhail Khodorkovsky on Sunday, his 48th birthday and eighth behind bars.
First Published: Sunday, June 26, 2011, 21:36