Russian opposition leader Alexei Navalny says he was briefly detained for organizing illegal protests as Russia prepares to hold presidential polls next month.

Navalny, who has been barred from challenging President Vladimir Putin in the election, now faces a court hearing and up to 30 days in prison after being formally charged.

The prominent Kremlin critic wrote on Twitter on Thursday afternoon: "I came out of the dentist's and what do you know -- the second operative (police) regiment, 'you're detained'."

He later wrote that he was taken to a police station where he was charged with repeatedly breaking rules on holding protests before being released.

"I've been released pending trial. I don't know when the hearing will be," he wrote on Twitter.

Navalny, who cannot contest the election because of a criminal conviction he says is politically-motivated, was detained last month after he appeared at a Moscow rally but released later that day without facing court.

He suggested the delayed hearing was a move by the Kremlin to ensure he would be in prison during the run-up to the election, which he has urged his supporters to boycott.

Navalny's campaign chief, Leonid Volkov, was almost simultaneously detained Thursday at a Moscow airport for reasons that were not immediately clear.

Volkov wrote on Twitter he had been held by police at Sheremetyevo airport where he was planning to fly to another Russian city.

On Tuesday, a Moscow court sentenced an ally of Navalny, Roman Rubanov, to 10 days in jail for posting a tweet urging supporters to attend the unauthorized January 28 rally.

Navalny was also questioned this month by investigators from the powerful Investigative Committee over an allegation that he attacked police during his detention after the protest.

Navalny has recently caused controversy with a viral video report alleging influential Russian Deputy Prime Minister Sergei Prikhodko enjoyed lavish hospitality from billionaire tycoon Oleg Deripaska.

On Wednesday, his anti-corruption foundation released a fresh YouTube video related to the allegations that has already been viewed more than 750,000 times.

Russia's media regulator last week blocked Navalny's website.

Both Deripaska and Prikhodko deny the allegations.

Navalny has faced a string of administrative and criminal charges that he and his supporters see as politically-motivated since he became the leading opposition figure campaigning against Putin's rule at mass rallies in 2011 and 2012.