Authorities in Moscow on Thursday raided the office of Alexei Navalny, Russia’s most outspoken critic of President Vladimir Putin and the governing United Russia party.

Navalny, 43, has been jailed repeatedly in recent years for organizing or participating in unsanctioned protests.

His organization, Foundation for Fighting Corruption, has produced reports alleging corruption at the highest levels of government, including Prime Minister Dmitry Medvedev.

Officers of the federal court bailiffs' service took Navalny from his office after forcing their way in. They later said Navalny hadn’t been detained.

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Navalny told reporters the raid was “part of the coordinated campaign against the anti-corruption foundation.”

“This complicates our work, but we will not halt it,” he said.

Lyubov Sobol, an attorney with Navalny's foundation, said the officers claimed to be searching for evidence connected to a case against the foundation's director, Ivan Zhdanov.

A criminal case was opened against Zhdanov in August for failing to follow an order to remove a 2017 video report claiming corruption by Medvedev, AFP reported. The video has racked nearly 33 million views on YouTube.

The raid came after Ruslan Shaveddinov, a project manager at Navalny's anti-corruption foundation, vanished on Monday and emerged the next day at a secret air defense base on a remote island in the Arctic Ocean, AFP reported.

Navalny said Wednesday that Shaveddinov had been forcibly drafted into the military -- a move his supporters have likened to a kidnapping. The 23-year-old reportedly was barred from communicating with the outside world or using a phone -- unlike other servicemen.

In a blog post, Navalny said Shaveddinov had been "unlawfully deprived of freedom" and was a "political prisoner."

The Russian military has denied the accusation, saying Shaveddinov had dodged his military service. Russian men between the ages of 18 and 27 are eligible for conspiration and serve for one year in the military.

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Navalny said Shaveddinov has had a medical condition that would legally disqualify him from military service.

The Associated Press contributed to this report.