Russian opposition leader Alexei Navalny was sentenced to 15 days behind bars and fined Monday after staging the biggest anti-corruption protests in years, an act branded a "provocation" by the Kremlin.
The Kremlin meanwhile rejected calls by the United States and the European Union on Monday to release over 1,000 opposition protesters detained during what it said were illegal demonstrations and accused organisers of paying teenagers to attend.
A Moscow district court ordered Navalny to serve 15 days in jail after finding him guilty of disobeying police orders. He was also fined 20,000 rubles ($350) for organising an unsanctioned protest.
The lawyer turned activist, 40, who has announced plans to run for president next year, called Sunday's protests after publishing a report accusing Prime Minister Dmitry Medvedev of controlling a property empire through a shadowy network of nonprofit organisations.
"The authorities are being accused of multi-million theft, but they remain silent," a haggard-looking Navalny said in court, insisting the protests were legal.
"More than 1,000 people were arrested yesterday (Sunday) but it is impossible to arrest millions," he said.
The protests, estimated to be the biggest since a wave of anti-Kremlin demonstrations in 2011-2012, come a year before a presidential election that Vladimir Putin is expected to contest, running for what would be a fourth term.
Medvedev's spokeswoman has called corruption allegations against him "propagandistic attacks", saying they amount to pre-election posturing by Navalny, who hopes to run against Putin next year.
Opinion polls suggest the liberal opposition, which Navalny represents, has little chance of fielding a candidate capable of unseating Putin, who enjoys high ratings. But Navalny and his supporters hope to channel public discontent over official corruption to attract more support.
The United States and the European Union both issued statements calling on Russia to free detained protesters, but Kremlin spokesman Dmitry Peskov said on Monday such calls were wide of the mark.
"We can't agree with these calls," Peskov told reporters on a conference call, saying the police had been professional and properly enforced Russian law.
He said the Kremlin had no problem with people expressing their opinions at protest meetings, but said the timing and location of such events had to be agreed with the authorities in advance, something which he said had not been done in large part on Sunday.
The authorities are concerned opposition activists will try to encourage people to break the law again in future, he said.
"We can't respect people who deliberately misled minors - in essence children - calling on them to take part in illegal actions in unsanctioned places and offering them certain rewards to do so, thus putting their lives at risk," said Peskov.
"What we saw yesterday in certain places, and especially in Moscow, was a provocation."
He said police had gathered factual evidence that some teenagers, who had been detained, had been paid cash by protest organisers to attend.
The Kremlin would listen to what people who took part in other sanctioned anti-government protests in some Russian cities had said on Sunday, Peskov promised.