A prominent Russian opposition leader was sentenced Thursday to 10 days in jail, a day after being arrested at a rally as activists try to keep up the pressure on President Vladimir Putin and his government.

Ilya Yashin was one of about 20 people arrested Wednesday night at Kudrinskaya Square, where anti-government demonstrators have gathered since their camp in a Moscow park was broken up by police earlier that day. He was sentenced for disobeying police.

Opposition activists for the past week have sought to establish a constant presence, a change of tactic since the massive anti-Putin protests that occurred over the winter. Those protests were sanctioned by authorities to take place at specific locations and times, and the demonstrations occurred at intervals of several weeks.

But after Putin's inauguration last week — he's back in the presidency for the third time — activists switched strategy, holding around-the-clock gatherings. The assemblies do not include posters, banners or public-address systems so that under Russian law they cannot be considered unauthorized protests.

But police broke up the first encampment, in the park that runs down the center of a leafy Moscow boulevard, after a court ruled in favor of a suit by neighborhood residents complaining of noise and disorder. The opposition then moved to Kudrinskaya Square, in the shadow of one of the city's iconic Stalinist Gothic skyscrapers.

Police have cracked down on any sign of that gathering's being turned into a permanent camp. Yashin and the others were arrested after police reportedly saw activists attempting to set up a field kitchen. On Thursday, two people were arrested after refusing police orders to remove food from the square's benches, the ITAR-Tass news agency reported.

Although only 20-30 people had remained on the square overnight, the crowd grew to several hundred on Thursday evening, news reports said.

The winter's protests were focused on calling for Putin's defeat in presidential elections. But he won handily and questions arose thereafter about whether the opposition would be able to maintain its momentum and whether authorities would crack down once he returned to office.

Over the past week, authorities have put several opposition leaders behind bars, threatened others with reprisals and proposed legislation introducing a 300-fold increase in the fine for taking part in unsanctioned rallies.

Some opposition leaders hope that the tough measures will foment anger and fuel bigger rallies. But others fear the repression will blunt the protest movement by scaring away many of the mostly middle-class protesters who turned out in the tens of thousands for peaceful demonstrations this winter.

On Thursday, Dmitry Medvedev, Putin's predecessor in the Kremlin and now prime minister, warned that authorities must become more flexible about protests.

"Everyone has to adapt, not just stiffen penalties or switch off Twitter during civil unrest," he said at the International Law Forum meeting in St. Petersburg. "Nobody is perfect, but we have to adapt to the new world."

Medvedev served as a presidential placeholder while Putin took a four-year sojourn as premier due to limits on consecutive presidential terms. He is seen as more reform-minded than Putin, but also as having relatively little ability to push through reforms.