MOSCOW (Reuters) - Russian opposition leader Alexei Navalny was briefly detained on Thursday and accused of organizing illegal protests, weeks before a presidential election in which he has been barred from running.

Russian opposition leader Alexei Navalny leaves the European court of Human Rights after a hearing regarding his case against Russia at the court in Strasbourg, France, January 24, 2018. REUTERS/Vincent Kessler

The 41-year-old anti-corruption campaigner was repeatedly jailed last year for organizing some of Russia’s biggest protests, targeting what he says are the luxury lifestyles of President Vladimir Putin and his inner circle.

Navalny’s detention on Thursday came shortly after his campaign chief, Leonid Volkov, tweeted that he had been detained at Moscow’s Sheremetyevo airport. Volkov later tweeted that he had been sentenced by a court to 30 days in jail.

Navalny said Volkov had been planning to fly to the Russian regional republic of Bashkortostan to organize election-monitoring activities.

Navalny’s spokeswoman, Kira Yarmysh, said Volkov had been found guilty of organizing illegal protests, and that it was “obvious” he was being punished for Navalny’s calls for a boycott of the March 18 election, which Putin is expected to win easily.

“As a high turnout is the Kremlin’s main goal, the authorities are very sensitive about our efforts to reduce it,” she said, adding that Navalny would keep up his calls.

Navalny has been barred from running in the election over what his supporters say is a trumped-up suspended prison sentence. Instead, he hopes for a boycott to undermine Putin’s legitimacy.

Navalny tweeted that he had been detained by police on Thursday as he left a dental appointment. He was released just under an hour later, saying police had opened a case against him for organizing illegal protests.

“They offered me a lift somewhere, but I declined and have gone to work. I don’t understand what happened and why it took seven people to detain me,” he said.

If found guilty, Navalny could also be jailed for 30 days, which would keep him behind bars until after the election.

INCREASING PRESSURE

Navalny has come under increasing pressure from authorities as he has sought to rally Russians against the election, which he says is a sham and a rigged contest.

Although Putin looks certain to secure a fourth term against rivals of little standing, analysts say the Kremlin is keen to boost his legitimacy with a high turnout, and avoid the impression that voters have stayed home in protest at falling living standards.

Navalny was detained at an anti-election protest in Moscow in late January and had his website blocked earlier this month after refusing to remove material covered in a court injunction.

Kremlin spokesman Dmitry Peskov did not immediately respond to a request for comment on Thursday but has previously said Navalny does not represent any real threat to Putin.

Yarmysh said the head of Navalny’s Anti-corruption Foundation had been sentenced to 10 days in jail on Tuesday for organizing an unsanctioned protest in January.