Russian opposition activist Alexei Navalny was briefly detained in Moscow on Thursday, ahead of the country’s presidential election from which he has been banned.
Navalny, the best-known political opponent of President Vladimir Putin, reported his detention in a series of tweets and said authorities had begun legal proceedings against him for organizing anti-government protests.
It’s not clear when he might face court, but he could be jailed for a maximum of 30 days and could possibly still be in prison for the March 18 election.
His chief of staff, Leonid Volkov, tweeted that he, too, had been detained.
The Kremlin appears to have made efforts to stifle the main opposition before the vote and Putin is expected to win by a landslide. Navalny is calling on Russians to boycott the election to strip Putin of his legitimacy.
He has been arrested many times, including in January, when he led the anti-Kremlin rallies, in which he called for the boycott.
Navalny has been barred from running because he carries a fraud conviction, which he has dismissed as a politically motivated move to keep him off the ballot.
The activist said on Twitter that he was detained by seven people as he came out of a dentist’s office after receiving treatment for a toothache.
In 2014, Putin signed into law tough restrictions on protests and public gatherings.
Navalny has risen to prominence in recent years by posting investigative stories online about the alleged corrupt practices of Russia’s elite.
Authorities recently shut down his website as well as several social media accounts.
The Kremlin rejects allegations of widespread high-level corruption and condemns Navalny as a dangerous threat to the country’s stability.
CNN’s Mary Ilyushina reported from Moscow with Angela Dewan reporting in London. CNN’s Carol Jordan also contributed to this report.