MOSCOW -- Russian opposition leader Alexei Navalny has been released from jail after serving 25 days for organizing a wave of protests.

Navalny was arrested June 12 as thousands of protesters gathered for an unsanctioned demonstration Moscow. Protests called for by Navalny occurred in more than 100 Russian cities and towns that day, one of the strongest showings by the marginalized opposition for several years.

Nearly 2,000 people were detained at the protests, most of them in Moscow and St. Petersburg.

Navalny's spokeswoman, Kira Yarmysh, tweeted photos of him arriving at his Fund For Fighting Corruption office Friday, but he made no immediate comment to the media.

Navalny, a Russian anti-corruption campaigner who is the most persistent thorn in the Kremlin's side, aims to run for Russian president in 2018.

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His released came as President Vladimir Putin was set to hold his first, much anticipated meeting with President Trump during a G20 summit in Hamburg, Germany.