Russian opposition activist Sergei Udaltsov has declared a hunger strike, after being sentenced to 10 days in prison for defying police during a demonstration against Vladimir Putin's presidential re-election.
Udaltsov, who leads Russia's Left Front movement, said Thursday the hunger strike was to protest the sentence.
Udaltsov has played a key role in organizing a series of opposition protests in Moscow against Mr. Putin's rule. He has been detained several times in the past few years in connection with similar charges.
In a separate case Thursday, businessman Alexei Kozlov was sent back to jail after a retrial of a controversial fraud case. Kozlov was sentenced to five years in jail and was immediately placed under arrest. He had already served three years in jail.
Kozlov's wife is a leading activist in the protest movement, and supporters say his sentence is related to her political activity.
Mr. Putin, who has been prime minister since relinquishing the presidency in 2008, won the March 4 presidential election by a landslide. He will be sworn in for a third term as president on May 7.