MOSCOW -- Russian police have searched the homes of leading opposition figures in an apparent crackdown on the eve of a planned mass protest against President Vladimir Putin's third term as president.
The opposition figures have been summoned for questioning by investigators on June 12 -- the same day as the planned protest.
Police, some armed with assault rifles, carried out searches on the homes of opposition figures including Boris Nemtsov, Ilya Yashin, Ksenia Sobchak, Sergei Udaltsov, Aleksei Navalny, and at least five others.
Udaltsov said police showed up at his door early in the morning.
"Police and Investigative Committee officers started banging on my door early in the morning, at 7 a.m. At the same time, they searched my parents' home," Udaltsov said. "They presented a search warrant as part of the criminal investigation of the events of May 6."
Udaltsov said police confiscated his computer, a flash stick, his iPad, and mobile telephone.
Sergei Udaltsov (left) and Aleksei Navalny speak at the May 6 opposition rally.
Udaltsov said he and his wife have been summoned to appear for questioning at the Federal Investigative Committee on June 12. Yashin, Navalny, and Sobchak were also summoned for questioning on June 12.
Rights activist Lev Ponomaryov called the searches "an attempt to disrupt" the Moscow protest and discourage attendance by opposition supporters.
"[The authorities have] several purposes here: To intimidate the organizers [of the planned June 12 protest], destabilize the leaders of the rally, and deliberately make people angry with these [home searches] so that more angry people come to this rally," Ponomaryov said.
"Using this opportunity, I call [on protesters] not to give in to this provocation. It is crucial to conduct the rally and the march tomorrow in a peaceful fashion."
The Federal Investigative Committee said the searches were connected to "mass disturbances" that occurred at a May 6 rally that ended with the arrests of hundreds of people after protesters clashed with police.
Police raid the apartment of opposition figure Aleksei Navalny on June 11.
"Investigators found it necessary to conduct these searches in the framework of a criminal investigation of mass disorders and the use of violence against the authorities after the detention and questioning of several participants in those mass disorders," committee spokesman Vladimir Markin told reporters in Moscow.
Opposition leaders could face up to 10 years in prison if they are charged and convicted of organizing mass disturbances.
The crackdown against the opposition comes days after Putin signed into law a controversial new measure that dramatically increases fines for those who participate in, or organize, demonstrations that have not been approved by authorities.
The planned demonstration on June 12 has been approved by the authorities, with the Moscow mayor's office giving permission for a rally of no more than 50,000 people. June 12 is a national holiday, with Russia observing Independence Day.
The protesters are seeking to call attention to alleged electoral fraud in December's parliamentary polls, the March presidential poll that reelected Putin, high-level corruption, and what they see as the damage Putin's continued rule is inflicting on Russia.
Putin has been in power as president or prime minister for the past 12 years.
Meanwhile, in related news, the U.S. State Department has voiced concern over the latest developments in Russia.
White House spokeswoman Victoria Nuland said that, what she called the "apparent harassment" of opposition figures, was clearly designed to take them off the streets during the demonstration on June 12.
She also criticized the new law in Russia imposing stiff penalties for violating rules on public demonstrations.
"Taken together, [recent measures against the opposition] raise serious questions about the arbitrary use of law enforcement to stifle free speech and free assembly [in Russia]," she said.
With reporting by ITAR-TASS, Reuters, AP, AFP, and Interfax