A Moscow court has sentenced the director of Russian opposition leader Aleksei Navalny's Anticorruption Foundation to 10 days in jail.

The Simonovsky district court on February 20 found Roman Rubanov guilty of organizing an unauthorized rally last month.

A senior Navalny associate, Leonid Volkov, said on Twitter late on February 19 that Rubanov was detained at Moscow's Sheremetyevo Airport after passing customs inspection.

On January 28, Navalny supporters nationwide staged "voter strike" demonstrations protesting the Central Election Commission's refusal to register Navalny as a presidential candidate and supporting his call for a boycott of the March 18 vote.

The commission disqualified Navalny because of a criminal conviction he contends was based on fabricated evidence.

Navalny has said the vote will not be a real, democratic election but the "reappointment" of President Vladimir Putin, who has been president or prime minister since 1999 and is seeking a new six-year term.

Navalny was himself arrested on his way to the January 28 protest in Moscow and was later released pending a court hearing. At least 350 people were detained nationwide.

Earlier on February 20, Navalny suggested that the timing of Rubanov's arrest was intended to keep him behind bars though March 18.

"Russian police sure [like] to "delay" the arrests of my associates, so that they spend the most important dates in detention," he tweeted.

Volkov missed the end of his election campaign, Navalny wrote, and now Rubanov "may miss the election day."

Navalny's Anticorruption Foundation has published several reports alleging corruption among associates of Putin, including one this month that documented what it said was a meeting on a yacht between tycoon Oleg Deripaska and Deputy Prime Minister Sergei Prikhodko, a former senior Kremlin adviser.

Nikita Kulachenkov of the Anticorruption Foundation also suggested that Rubanov's detainment came weeks after the January 28 rallies in order to keep him out of action on Election Day.

Kulachenkov wrote on the foundation's website on February 20 that since Russian law does not allow the duration of administrative arrest to exceed 30 days, authorities often detain key opposition activists closer to important dates in order to keep them isolated.

Eight candidates will be on the ballot in the presidential vote. Putin's popularity, his control over the levers of power, and what critics say have been years of steps to suppress dissent and marginalize opponents virtually ensure that he will win a fourth term.

Opposition activists say that in past elections the Kremlin has used an array of tactics, both during campaigns and on election day, to manipulate the vote and achieve the results it desires.

Russia's constitution bars presidents from serving more than two consecutive terms, meaning that Putin would not be eligible to seek a new term in 2024.

A longtime KGB officer in the Soviet era, Putin served two four-year terms after President Boris Yeltsin stepped down on the last day of 1999 and put him in charge as acting president.

After steering Dmitry Medvedev into the presidency in 2008 and becoming prime minister -- a move that enabled him to retain power without violating the constitutional limit of two straight terms -- Putin returned to the Kremlin in 2012.