Anonymous bomb threats that had prompted mass evacuations in several Russian cities have resumed.

Local officials said thousands were evacuated on December 20 from administrative buildings, schools, universities, shopping malls, markets, hospitals, and hotels in Moscow, Stavropol, Cherkessk, and Petropavlovsk-Kamchatsky.

A spate of telephone bomb threats that proved to be hoaxes had targeted some 3,500 public buildings in 190 Russian cities and led to the evacuation of more than 2.3 million people in September, Russian officials said.

Bombs were never discovered in any of the cases.

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.

On December 12, Deputy Interior Minister Igor Zubov said that most of the phone bomb threats came from Syria. He also named Turkey, Ukraine, the United States, Canada, Kazakhstan, and Uzbekistan as places from where the phone calls were made.

President Vladimir Putin's spokesman, Dmitry Peskov has called the threats "telephone terrorism."

With reporting by mskagency.ru, Interfax, and RIA Novosti