MOSCOW -- A Moscow court has sentenced seven of the eight defendants in the Bolotnaya Square case to jail terms of between 2 1/2 to four years.
One defendant, Aleksandra Naumova-Dukhanina -- the only woman among the defendants -- received a suspended sentence.
The eight were found guilty on February 21 of rioting and assaulting police. Lawyers for the defendants said they will appeal.
Outside the court during sentencing on February 24, police detained at least 230 protesters, including opposition figure Aleksei Navalny, and two founding members of Pussy Riot -- Maria Alyokhina and Nadezhda Tolokonnikova -- as well as the latter's husband, Pyotr Verzilov.
WATCH: Police Detain Protesters As Bolotnaya Trial Ends
Police said the demonstrators -- some of whom shouted slogans referring to the government overthrow in Ukraine -- were being held on suspicion of violating public order.
In a statement, Amnesty International said the detention of the protesters indicated that "the Russian authorities' rampant violation of freedom of expression and assembly shows no sign of letting up."
The head of the human rights group's Moscow office, Sergei Nikitin, told Interfax that the February 24 sentences were a "parody of justice" and called for the convicts' immediate release.
The U.S. State Department has denounced the convictions as "politically motivated."
"The situation is a total mess. The police insist we are obstructing other citizens from using the sidewalk," one protester told RFE/RL. "However, it's clear that there's ample space -- perhaps a good 6 meters of it -- for anybody to pass by freely. They are telling outright lies."
The European Union's foreign-policy chief, Catherine Ashton, described the sentences handed down to the Bolotnaya defendants as "disproportionate," and called for them to be reduced on appeal.
A prominent Russian human rights activist, Lyudmila Alekseyeva, a founding member of the Moscow Helsinki Watch group, denounced the prison terms as "unfair."
"Because the main part of the verdict is based on charges of mass riots. And there were no mass riots. It is a lie, and the judge knows it, and those who gave false evidence know it -- there were no mass riots," Alekseyeva added.
"Compared to what is happening in other countries, can we say that what happened on May 6 were mass riots? It is worse than a lie -- it's silly."
A Post-Sochi Warning
The eight were arrested during an officially approved rally on May 6, 2012, on Moscow's Bolotnaya Square. The rally occurred one day before Vladimir Putin returned to the Kremlin to start an unprecedented third term as president.
The protesters accused Putin and his party of electoral fraud, corruption, and damaging Russia with authoritarian rule.
At the trial, the defendants pleaded not guilty to attacking police and instead accused police of being responsible for the clashes that erupted at the demonstration.
Reacting to the sentencing, Kremlin spokesman Dmitry Peskov said the Bolotnaya convicts would be able to appeal for a pardon from Putin.
In December, former Yukos oil tycoon Mikhail Khodorkovsky was pardoned and Pussy Riot founders Alyokhina and Tolokonnikova were released from prison under an amnesty. They were seen by Western rights groups as having been imprisoned on politically motivated charges over their anti-Kremlin activity.
Some supporters of the Bolotnaya convicts alleged that the court handed down harsher sentences than usual in response to the Ukrainian upheaval, with the authorities seeking to send a warning to Russians contemplating launching a similar antigovernment movement.
Critics of the case have also alleged that the sentencing was postponed until February 24 in a bid by the authorities to avoid controversial news from Russia as the Sochi Winter Olympics drew to a close the day before.
Vyacheslav Makarov, a lawyer for Bolotnaya defendant Sergei Krivov, who was sentenced to four years in jail, told RFE/RL that the sentence was unjustifiably severe and that an appeal was planned.
"If he was given a suspended sentence, I think Sergei would have supported me and we would have appealed that, too. Since he is absolutely innocent, he didn't deserve this sentence," Makarov said.
"What's more, he was assaulted by police during a sanctioned, authorized demonstration."
Two antigovernment activists are being tried in a separate case on charges of plotting the violence at Bolotnaya Square.
Sergei Udaltsov and Leonid Razvozzhayev pleaded not guilty in court last week. They accuse the authorities of cracking down on anyone who dares oppose Putin's rule.
With reporting by ITAR-TASS, Interfax, and Reuters