MOSCOW — Russian opposition leader Alexei Navalny, who organized a wave of nationwide protests against government corruption that rattled authorities, was jailed for 15 days today by a Moscow court for resisting police orders.

Navalny was arrested Sunday as he walked to a protest in Moscow and spent the night in jail before appearing in court.

Tens of thousands of anti-corruption protesters took to the streets across Russia on Sunday in the biggest show of defiance since 2011-2012 anti-government protests.

Journalists and well-wishers today packed the courtroom in central Moscow where Navalny was taken. He posted a selfie on Twitter from the courtroom, saying: “A time will come when we’ll put them on trial too — and that time it will be fair.”

The 40-year-old Navalny, Russia’s most popular, charismatic opposition leader, has been twice convicted on fraud and embezzlement charges that he has dismissed as politically motivated. Navalny, who is currently serving a suspended sentence, has also recently announced his bid for the presidency in Russia’s 2018 election.

“Even the slightest illusion of fair justice is absent here,” Navalny told reporters today at the defendant’s bench, complaining about the judge striking down one motion after another. “Yesterday’s events have shown that quite a large number of voters in Russia support the program of a candidate who stands for fighting corruption. These people demand political representation — and I strive to be their political representative.”