Alexei Navalny, Putin thorn, is jailed again in Russia

A court in Moscow has sentenced Russian opposition leader Alexei Navalny to 30 days in jail for staging an unsanctioned protest in the capital.

Navalny organized a series of protests on May 5 in Moscow and other Russian cities before President Vladimir Putin's inauguration for a new term. Demonstrations under the slogan "He is not our czar" took place in many cities throughout the country.

Moscow's Tverskoy District Court convicted Navalny on Tuesday on charges of organizing an unauthorized rally and ordered him jailed for 30 days.

Navalny, who will turn 42 on June 4, argued that the authorities' refusal to allow the protest was illegal and criticized the accusations against him as "ridiculous and unlawful."

The anti-corruption campaigner, who has become Putin's most visible foe, has served several weeks-long jail terms for organizing protests.

He was barred from running in the most recent election as a result and called for a boycott of the vote.