Russian opposition politician Ilya Yashin was detained moments after his release from jail on Sunday after completing a 10-day sentence for his role in Moscow's recent wave of protests.
"I have been detained once again outside the jail," Yashin said on his Twitter account.
He posted a video of a policeman saying he was being detained for urging people to take part in unsanctioned protests. The video shows Yashin being escorted into a police van.
Yashin was one of several opposition figures excluded from Moscow's upcoming local elections, triggering a month of protests in the Russian capital.
Sunday's scenario was the same as that following a 10-day sentence meted out after Yashin was arrested ahead of a July 27 unsanctioned protest in Moscow that led to more than 1,400 arrests.
After completing the term, he was detained upon his release on August 8 and given an additional 10 days in jail.
The Russian opposition has staged several large protests in Moscow this month demanding free elections.
The rallies were the biggest since mass protests broke out in 2011 against President Vladimir Putin's return to the Kremlin after a term as prime minister.
Police have come down hard on the demonstrations, which have tapped into wider anger over declining living standards and a stalling economy.
Some 3,000 people have been arrested for taking part and prominent members of the opposition, including top Kremlin critic Alexei Navalny, remain behind bars.
The Moscow city hall elections were, until last month, a relatively minor event on Russia's political calendar.
But the issue blew up after election authorities refused to register various opposition candidates over alleged violations including faking the signatures needed to qualify.
Local polls are a rare opportunity for dissenting voices to participate in political life as anti-Kremlin parties have been squeezed out of parliament over Putin's two decades in power.