Russian opposition leader Alexei Navalny has been detained by police after breaking house arrest to join an opposition rally in Moscow.
"I was detained," Navalny said on his Twitter account on Tuesday. "But they won't be able to detain everyone".
A Russian court gave Navalny a suspended sentence for embezzling money but jailed his brother for three-and-a-half years in a case seen as part of a campaign to stifle dissent.
Navalny has been under house arrest since February under the conditions of the ongoing court case.
About 2,000 people rallied near Red Square on the evening after the sentencing, responding to Navalny's call for mass protests to "destroy" President Vladimir Putin's regime.
The gathering near the Kremlin fell far short of the 18,000 who pledged to attend on social media.
Police detained more than 130 demonstrators during the protests according to OVD-Info, a group which tracks arrests.
Many were yelling things like "Freedom!" and "We are the power."
A Moscow judge on Tuesday found both Navalny and his brother Oleg guilty of embezzlement and sentenced them to three and a half years in what is widely seen as a politically motivated case.
The hearing was abruptly brought forward by two weeks in what many see as a bid to prevent protests because demonstrators would not be able to organise the required permission.
But while Navalny's sentence was suspended, his younger brother, who is not involved in politics, was ordered to serve the time behind bars in what observers saw as an attempt to muzzle the Kremlin critic ahead of the 2018 presidential election by taking his brother hostage.
"This regime does not just destroy its political opponents... now they target, torture and torment the relatives of its political opponents," the 38-year-old Navalny said outside court, calling the verdict "the most mean and disgusting" possible.
"This regime has no right to exist, it must be destroyed," he said. "I call on everyone to take to the streets today."
The protest has not received the required authorisation from city hall, which ominously warned that "all unsanctioned actions will be prevented by the security forces".
Navalny has become a major thorn in the Kremlin's side over the last few years, first building a massive support base on the Internet as an anti-corruption blogger, then rallying tens of thousands during the 2011-12 anti-Putin protests. He also came second in last year's Moscow mayoral race after a grassroots campaign against the Kremlin-backed candidate.
The Navalny brothers were accused of defrauding French cosmetics company Yves Rocher of nearly 27 million rubles (more than half a million dollars at the exchange rate at the time), although the firm has said that it suffered no damages.
Prosecutors had asked the court to jail Navalny for 10 years and Oleg for eight.
Tuesday's hearing was brought forward two weeks in a move seen as a tactic to avoid massive protests and make it impossible to request authorisation for rallies.
The session took only about 15 minutes, unusual for Russia where judges usually read sentences for hours.
"What are you jailing him for, what sort of disgrace is this? This is to punish me even more?" Navalny yelled, slamming his fists on the table, as the judge announced that his 31-year-old brother, a father of two young children, would be jailed.
Source: Al Jazeera and agencies