Several thousand people have been evacuated from Moscow's famous Bolshoi Theater after bomb threats were received.
Russia's state TASS news agency said more than 3,500 people were evacuated on November 5 before a performance was due to start.
Tens of thousands of people have been evacuated from schools, malls, theaters, universities, hotels, and government buildings in cities nationwide amid a wave of anonymous bomb threats that began on September 10.
Bombs have not been discovered in any of the cases.
The Metropol hotel and GUM department store on Red Square were also evacuated on November 5.
Federal Security Service (FSB) Director Aleksandr Bortnikov said on October 5 that four Russian citizens suspected of organizing the wave of anonymous bomb threats had been identified.
Bortnikov said that the four suspects are living abroad and have accomplices inside Russia.
Kremlin spokesman Dmitry Peskov said in September that the threats are "telephone terrorism" and that "all necessary measures are being taken" to find the perpetrators.