Updated

A top Russian official says most of the fake bomb calls that have plagued cities across Russia have come from Syria.

Deputy Interior Minister Igor Zubov said Tuesday in remarks carried by Russian news agencies that most of the anonymous calls came from areas controlled by "terrorists" in Syria.

Russia has waged a military campaign in Syria since September 2015, allowing Syrian President Bashar Assad's government to win back control over most of the country.

Zubov said fake bomb threats have also come from Turkey, Ukraine, the U.S. and Canada, and a few calls came from the ex-Soviet nations of Kazakhstan and Uzbekistan.

Russian officials say a slew of fake bomb calls have targeted 3,500 buildings in 190 Russian cities and led to the evacuation of more than 2.5 million people since September.