Russian government critic Alexei Navalny was sentenced to 30 days in prison on Wednesday for urging a major rally as his allies were targeted with a criminal investigation.

Authorities made the move as they seek to clamp down on attempts to create a new wave of demonstrations.

The anti-corruption campaigner said in an Instagram video that police had picked him up outside his Moscow apartment as he left to go jogging.

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"People are right when they say that sport is not always good for your health," the 43-year-old joked. "I have been detained and am now at a police station wearing shorts like a stupid man."

Weeks of rallies

Protesters have rallied in the Russian capital over the past several weeks against authorities' refusal to put independent opposition candidates on the ballot for September local elections.

More than 20,000 people attended last weekend's demonstration and Navalny had called for an even larger rally on Saturday in front of city hall. 

Election authorities said they blocked a number of independent opposition politicians and local activists, accusing them of faking signatures to get on the ballot. In Russia, candidates outside the large parliamentary parties must gather signatures to stand for election. 

The barred candidates claim the move is blatantly political.

Much of the opposition opposes Sergei Sobyanin, a loyalist supporter of President Vladimir Putin who appointed him Moscow mayor in 2010.

In the last city election on 2013, Navalny came in second in the mayoral contests against Sobyanin in a vote the opposition claimed was marred by irregularities.

Over the past decade, Navalny has repeatedly been threatened, arrested or jailed as he emerged as one of the main opponents of Putin. His political allies have faced similar treatment. 

Last year, Navalny was jailed for 30 days, and then another 20-day stint upon his release in September. 

In April, the European Court of Human Rights ruled Russia violated Navalny's rights by holding him under house arrest for most of 2014 during an embezzlement case. 

He was barred from contesting Putin in last year's presidential election, in what critics said was a clear move to prevent a challenge from the Kremlin's most popular opposition figure.   

cw/msh (AFP, Reuters)